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Book._' 514 _ 

GoKiight N n _\ Q/ ?)S 


COPYRIGHT DEPOSFT. 











The Joy of Health and Strength: a Football Game 



GENERAL HYGIENE 


REVISED 


BY 

FRANK OVERTON, M.D., Dr.P.H., Sc.D 

w 

AUTHOR OF “APPLIED PHYSIOLOGY” 

SANITARY SUPERVISOR 

NEW YORK STATE DEPARTMENT OF HEALTH 




AMERICAN BOOK COMPANY 

NEW YORK CINCINNATI CHICAGO 

BOSTON ATLANTA 













Copyright, 1913, by 

FRANK OVERTON. 

Copyright, 1923, by 

AMERICAN BOOK COMPANY. 

Copyright, 1913, in Great Britain. 

OVERTON, GENERAL HYGIENE, REVISED. 
E. P. I 


MADE IN TJ.S.A 



GC1A704042 




PREFACE 


The knowledge gained by scientific research in hygiene 
has been standardized and simplified, and the average 
person can now apply hygienic principles to daily living as 
accurately as he can apply the scientific principles of me¬ 
chanical engineering to automobiling and radio telephoning. 
An ordinary person can now operate and care for the ma¬ 
chinery of his body with intelligence and certainty. 

This book supplements the author’s u Personal Hygiene, 
Revised” and is designed for pupils in the sixth, seventh, 
and eighth grades. It supplies the kind of hygienic in¬ 
formation which physicians and health officers have found 
that the people need. It is also a guide to teachers in super¬ 
vising and advising the pupils in their health habits and 
actions, and in directing them to observe the sanitary ar¬ 
rangements and practices in the school, the home, and the 
community. 

The scientific information contained in this book is of 
a grade commensurate with the mental age of the pupils 
for whom it is designed. While “ Personal Hygiene, Re¬ 
vised” dwells upon the practice of health chores by the 
individual pupils, “ General Hygiene, Revised” emphasizes 
civic responsibilities, and will prepare the pupils for their 
future duties along public health lines. 

The pupils who will use this book have the mental capac¬ 
ity and attainments of the average voting citizen, and can 
readily understand the principles on which modern public 

5 


6 


PREFACE 


health movements are founded. About twenty-five years, 
or a generation of time, have hitherto been required for 
a knowledge of current progress in medicine and hygiene 
to become the common possession of the people ; but proper 
hygienic instruction in the school would reduce the years 
to less than ten, or the time which a pupil usually spends 
in a public school. The citizen who is properly informed 
regarding the possibilities of attaining physical and mental 
health will do what he can to make that knowledge avail¬ 
able to all the people. This book supplies the practical 
information which the future citizen will wish to trans¬ 
form into intelligent action. 

Every effort has been put forth to make the book attrac¬ 
tive as well as truthful. The text is written in simple Eng¬ 
lish which can be easily read and understood. The illus¬ 
trations are largely new, and are designed to visualize and 
vitalize the text. While nearly all the cuts are from designs 
or photograph? made by the author, the one on page 11 is 
from a painting owned by the Arlington Chemical Com¬ 
pany, and reproduced by their permission. 

The demonstrations and experiments have practical 
bearings on hygienic living, and can be performed with the 
facilities which are available in every school. The obser¬ 
vations which are suggested for the pupils to make are of 
matters which are of public interest in every community. 
The whole plan and execution of the book is in accordance 
with the best pedagogical standards. 


CONTENTS 


CHAPTER PAGE 

I. The Study of Hygiene 

II. Organs and Cells 

III. Composition of the Body 
I.V. Disease Germs 

V. Department of Health 

VI. Stimulants and Narcotics 

VII. Bones and Joints 
VIII. Muscles 


IX. Circulation of Blood.94 

X. Emergencies .m 

XI. Respiration. .129 

XII. Hindrances to Breathing.138 

XIII. Foul Air.148 

XIV. Ventilation.161 

XV. Body Heat. .170 

XVI. The Skin.184 

XVII. The Wastes of the Body ..... 197 

XVIII. Water Supply.212 

XIX. Vermin.227 

XX. Food Elements.240 

XXI. Digestion.254 

XXII. Absorption and Assimilation . . . .265 

XXIII. Foodstuffs.276 

XXIV. Wholesome Food . . . . . . 290 

XXV. Care of the Nose and Mouth . . . -303 


20 

30 

37 

48 

58 

68 


7 







8 


CONTENTS 


CHAPTER 

XXVI. 

Infectious Diseases 

• • • 

# 

PAGE 

• 313 

XXVII. 

Prevention of Infectious 

Diseases . 

. 

• 327 

XXVIII. 

Tuberculosis 

• • 

• 


• 351 

XXIX. 

The Nervous 

System . 

• 


. 361 

XXX. 

The Brain 

• 

• • • 


• 372 

XXXI. 

The Senses . 


• • • 


• 391 

XXXII. 

TAe Eye 

. 

• • • 


. 400 

XXXIII. 

The Voice 

• • 

. 


. 412 

GLOSSARY . 

• 

. 

• 

. 417’ 

INDEX 





• 425 






GENERAL HYGIENE 



Body and Mind Working Together Perfectly 


CHAPTER I 

THE STUDY OF HYGIENE 

Body and Mind. — The body is a living machine, 
and the mind is the engineer that controls it. The 
body is useless without the mind, and the mind can 
do nothing except by means of the body. The two 
must work together. When either one is out of order, 
the other also suffers. 

One of the greatest of all the differences between 
a man and a tree is that a man has a mind, while a 


9 














IO 


THE STUDY OF HYGIENE 


tree has none. A tree grows in the way in which the 
soil, the weather, and other trees compel it to grow. 
But a man can use his mind to choose his home, his 
food, the air which he breathes, and the work which he 
does. He can avoid those things which will harm his 
body, and can do those things which will keep it strong 
and sound. If a person’s body is in good order, we say 
that he is healthy. 

The Joy of Health and Strength. —The mind- 
takes delight in directing the actions of a sound body. 
A healthy boy runs for the fun of running fast, and 
climbs hills and trees for the pleasure of using his 
strength. He studies difficult lessons for the joy of 
thinking, and puts his whole mind to a puzzle for the 
delight of solving it. He has no pains or other un¬ 
comfortable feelings, and he performs all his actions 
so smoothly and easily that he almost forgets he has 
a body. - 

Most boys and girls do not always feel bright and 
active, but sometimes they have aches and pains in 
their bodies, and are too weak to work or play or 
think. When they feel like this, they are either over¬ 
tired or sick. 

Is Sickness Necessary? — People used to think that 

sickness was necessary. They supposed that diseases 
were caused by bad weather and by mighty powers 
in the air or ground, just as they supposed storms 
and earthquakes were caused. They thought that 
sickness could no more be prevented than rainy days. 




THE STUDY OF HYGIENE 


11 



Painting tyj IF. Granville-Smilh 

Storm and Sickness 

A doctor’s visit during a snowstorm. It was formerly supposed that bad weather 

was the principal cause of sickness. 

Now we know that most forms of sickness come from 
causes which can readily be prevented, such as dirt, 
spoiled food, foul air, and wrong eating. A school 
child can understand how the common forms of sick¬ 
ness are caused, and how they may be prevented. 

Progress in Health Matters. — In the United States 
there are always over a million persons who are sick. 
About two hundred thousand doctors are occupied in 
caring for them. The expenses of the sickness and the 
value of the time lost by the sick are at least a billion 
dollars a year. But no one can estimate the suffering 
and anxiety which are borne by the sick and their 
friends. 

There is not so much sickness among civilized nations 





12 


THE STUDY OF HYGIENE 


now as formerly. We know this from a study of the 
records of deaths, and from the history of epidemics. 

i. The death rate of a country is the number of 
persons dying each year in every thousand inhabitants. 
The governments of all civilized lands have long been 
keeping records of all persons who die in those countries. 
Before the year 1800, about fifty or sixty persons in 
every thousand inhabitants died each year in England, 
Germany, and the United States. Now, in these 
countries, only about fourteen persons die in every 
thousand inhabitants. But in India the death rate is 
now as high as it was in England a century ago. This 
is because the people of India are as ignorant of health 
matters now as the people of England were a century ago. 

The average age at which persons die in civilized 
lands is now nearly double the average age at which 
they died a century ago. The tombs and mummies of 
ancient Egypt show that the Egyptians died at an 
average age of about twenty-two years. In the city 
of Geneva, Switzerland, the average age of persons dy¬ 
ing in the year 1600 was twenty-one years; in 1700, 
thirty-two years; in 1800, thirty-eight years. Now, 
the average age of those dying in the United States is 
over fifty years. But in India and Russia the average 
age at death is now about twenty-five years, or about 
the same as it was in ancient Egypt. The people of 
those countries which are the most advanced in civi¬ 
lization and knowledge live about twice as long as the 
people of the less civilized lands. 


THE STUDY OF HYGIENE 


13 



Man-Made Causes of Sickness 

Garbage and sewage at the back door of a restaurant. It is now known that most 
human sickness comes from unsanitary conditions which are made by man himself. 


2. A disease which spreads through a whole town 
or country is called an epidem'ic or a pestilence. The 
people of olden times were always in fear of war and 
pestilence. Thousands of men were killed each year 
by useless and cruel wars, but millions of men, women, 
and children were killed by diseases which are now 
seldom seen. In England in the fourteenth century, 
half of the population died from the plague in a single 
year. One hundred and two English colonists landed 
at Plymouth, Massachusetts, in December, 1620, and 
before the next spring fifty-two of them had died from 
what was probably typhus (tl'fus) fever. In 1879 
one tenth of the inhabitants of the Philippine Islands 
died from cholera (kol'er-a). The plague, typhus 



















14 


THE STUDY OF HYGIENE 


fever, and cholera are now almost unknown among most 
civilized peoples, but these diseases still go on in India 
and other less advanced lands. Now and then a few 
cases reach the United States, but the diseases do not 
spread because great care is taken to check them. 

Cause of Epidemics. — The great epidemics of olden 
times were spread in very simple ways, and could easily 
have been prevented. The plague was spread by rats 
and fleas which swarmed over the thatched roofs and 
mud floors of the huts of the people. About the year 
1900 the plague was brought to San Francisco by 
rats that came on ships from foreign lands; but the 
disease was stopped by making the foundations and 
cellars of the buildings ratproof, so that the animals 
could not find hiding places. 

Typhus fever is caused by body lice and spreads 
among people who are overcrowded. This accounts 
for the large death rate among the colonists of Ply¬ 
mouth, who were badly overcrowded both on their 
ship and in their houses, and who had no proper means 
of bathing and of removing lice, and no way of separat¬ 
ing the sick from the well. To-day, there is hardly a 
place in the United States where people have to live in 
the way the colonists lived, and therefore typhus fever 
is almost unknown in this country. 

Cholera is spread principally among those who drink 
impure water. In 1832 an epidemic of cholera broke 
out in New York, and all the people who could get away 
from the city left it in terror. At that time the drink- 


THE STUDY OF HYGIENE 


US 



The Croton Aqueduct over the Harlem River 

* 

This aqueduct, completed in 1840, brought pure water to the city of New York, 

and ended the danger of cholera. 


ing water was drawn from wells which were dug along 
the edges of the streets, and into which slops and gar¬ 
bage thrown upon the ground, could drain. There¬ 
fore people were made ill from drinking the im¬ 
pure water from these wells. In 1840 pure water was 
brought to the city through the Croton aqueduct, and 
since that time the people of New York have not been 
in real danger of cholera. 

These examples are given to show the simple nature 
of the causes of most diseases, and how they are in our 
control. It is not nice to have rats in our houses; it 
is not fashionable to be dirty; and we are ashamed to 
have a bad odor about our clothes or houses. But the 

0 

feelings which well-bred persons have about dirt and 
bad odors are not founded merely upon style and show. 









i6 


THE STUDY OF HYGIENE 


Failure to keep rats and other vermin out of our houses, 
and failure to keep clean, would mean sickness and 
death now, just as in olden times. You may prevent a 
great deal of sickness by doing the simple things which 
every polite and thoughtful person in a modern 
community is expected to do. 

Diseases of the Present. — Lep'rosy, plague, typhus 
fever, and smallpox were formerly extremely common 
in all civilized lands. Now, they seldom occur. 
Yellow fever and malaria have been wiped out of Pan¬ 
ama simply by the extermination of the mosquitoes 
there. But a great deal still remains to be done. Only 
about one third of all deaths in the United States are 
due to old age, and over half are caused by diseases 
which may easily be prevented. Typhoid (tl'foid) 
fever is still a common disease, and colds are ex¬ 
tremely common. Tuberculosis is now so common 
that it is called the great white plague , and one tenth of 
all deaths among white races are due to it. We think it 
is a terrible thing that one tenth of the people of the 
Philippine Islands should have died from cholera in 
1879, an d yet one person in every ten who now live in 
the United States will die from tuberculosis, unless a 
great deal more is done in the near future than has 
been done in the past to prevent the disease. 

Helping Each Other to Keep Well. — You cannot 
keep well by thinking of yourself alone. You must 
think of the health of others in order to protect your 
own health. If you carelessly allow some one to catch 



THE STUDY OF HYGIENE 


17 


tonsillitis (ton-si-ll'tis) from you, he may give the 
disease to a third person, who may give the disease 
back to you a month or two after you recover from 
your first sickness. 

You will often be soiled with dust from streets over 
which diseased persons and animals have scattered the 
germs of sickness. You will often breathe air which 
the sick have breathed, and will often buy food which 
has been handled by unhealthy persons. What others 
do will affect your own health, and what you do will 
affect the health of other persons. You are only one 
among hundreds of the inhabitants of a town, but the 
healthfulness of your town will depend on what each 
separate inhabitant does. When you help others to 
keep well, you also help yourself to be healthy. 

Teaching the Care of Health. — A little child learns 
a great deal about the care of his body from his parents. 
When he goes to school, he learns more about its care 
from his teachers, and from the books which he studies. 
Later in life he learns still more from the advice of 
doctors, from public lectures, and from articles in 
books, newspapers, and magazines. 

Public schools are among the best of all means for 
teaching the preservation of health. Most states now 
have laws that every public school shall teach its pupils 
how to take care of their bodies, and how to prevent dis¬ 
eases. If all boys and girls will learn to do their part 
in the promotion of health, the next generation of men 
and women will be a vigorous, happy race. Colds 


OV. GEN. HYG. — 2 



i8 


THE STUDY OF HYGIENE 


and tuberculosis will be as rare as leprosy is now. 
Nearly all will live to a ripe old age, and sickness and 
pain will be almost unknown. No one will feel that 
life is a burden, but all will feel the joy that comes 
from health and strength (p. io). 

Hygiene. — The study of keeping the body in good 
health is called hygiene (hi'ji-en). In it you will study 
such subjects as bathing, eating, drinking, clothing, 
breathing, exercise, and sleep. 

Hygiene also includes the study of the methods and 
conditions by which diseases are prevented. It there¬ 
fore treats of such subjects as pure food, wholesome 
drinking water, fresh air, and the disposal of sewage. 

Anatomy and Physiology. — Before you can under¬ 
stand the care of the body, you must know something 
about the structure of its machinery, and how it 
does its work. The study of the structure of the body 
is called anat'omy , and the study of its work and action 
is called physiol'ogy. You must study the anatomy and 
physiology of each part of the body in order to under¬ 
stand the care of it. 


QUESTIONS 

What are some of the signs of good health ? 

What are some of the signs of poor health? 

What effect does sickness of the body have upon the mind? 

About how many persons in the United States are sick at one time? 
About how much money does sickness cost the people of the United 
States each year? 

Give some reasons for thinking that there is less sickness now than 
formerly. 


THE STUDY OF HYGIENE 


19 


What is the average death rate in the United States? 

What is the average length of life in the United States? 

What is an epidemic? 

Name some epidemics which used to be common, but now seldom 
occur. 

What are some of the reasons why deadly epidemics no longer 
occur? 

Name some deadly diseases which are now common. 

How does a person protect his own health when he helps others 
to keep well? 

What is hygiene? 

What is physiology ? 

What is anatomy? 

What is the object of teaching hygiene in schools? 

For the Teacher. — The object of the study of hygiene is to cause the pupils 
to desire to maintain the machinery of their bodies in an efficient working state. 
Call attention to the dangers to which early men were subjected : — as storms 
and cold weather; wild animals and savage men ; famine and war. Describe 
the means by which these dangers have been lessened. 

Epidemic diseases were the next great dangers which threatened the exist¬ 
ence of the human race. Many of these have been conquered, but others still 
remain, and apparently new diseases appear. Modern modes of life bring new 
dangers from speeding automobiles, whirling machinery, and the close associa¬ 
tion of crowds. 

While great progress has been made in the past, yet still greater will be 
made in the future, if every pupil is instructed in the working of his body ma¬ 
chinery and the means of keeping it in good order. 


CHAPTER II 


ORGANS AND CELLS 

Life and Growth. — The food upon which the body 
lives has no life, but it becomes living blood, flesh, and 
bone in the body. After remaining alive for a few 
days or weeks, the living flesh becomes worn out and is 
changed back to dead and lifeless forms, and new flesh 
is formed to take its place. 

The constant building up of worn-out parts of the 
body is what is called life and growth. Lifeless things 
change and go to pieces, and cannot build themselves 
up again. Living things are said to be alive because 
they build themselves up as fast as they wear out. 

The actions of growth and repair are only slightly 
under the control of the mind, and so go on while a 
person is asleep even better than they do while he is 
awake. The same kinds of action go on in a tree, 
which has no mind at all. 

Division of Labor in the Body. — Each action of the 
human body takes place in a particular part. One part 
of the body prepares food, another supplies air to all 
the rest of the body, other parts carry the food and air 
through the body, and others get rid of the worn-out 
food and flesh. A part of the body which has a par¬ 
ticular work to do is called an organ. 


20 


ORGANS AND CELLS 


21 


Brain 


Spinal cord 


Organs of Digestion. — The action of changing food 
to forms which living flesh can use is called digestion. 
There are five principal 
organs of digestion : i, the 
mouth; 2, a bag, called 
the stomach , which receives 
the food when it is swal¬ 
lowed ; 3, a long tube, 

called the intestine (in- 
tesTin), in which the food 
is dissolved; 4, a mass of 
flesh, called the pan'creas , 
in which a liquid is pre¬ 
pared for dissolving the 
food; and 5, a large mass 
of flesh, called the liver, in 
which food is made a part 
of the blood. 

Organs of Respiration. 

The body cannot work, 
or even live, unless a con¬ 
stant supply of oxygen 
(ok'si-jen) from the air 
reaches every part. 

Breathing, and the changes 
produced by the oxygen in the body, are called respira¬ 
tion. The principal organs of respiration are the lungs. 

Organs of Circulation. — Blood carries oxygen and di¬ 
gested food through all parts of the body, and its flow 



Lungs 


Heart 

Diaphragm 


Liver 


Stomach 

Kidney 

1 

^ Intestine 


Diagram of the Position of the 
Principal Organs of the Body 























22 


ORGANS AND CELLS 


is called the circulation. There are two principal or¬ 
gans of circulation: i, a pump, called the heart , which 
keeps the blood in motion; and 2, a vast number of 
tubes, which conduct the blood through the body. 

Organs of Excretion. — Getting rid of worn-out 
substances is called excretion. There are three princi¬ 
pal organs of excretion: 
the kidneys, the skin, and 
the lungs. The liver and 
the intestine are also im¬ 
portant organs of excre¬ 
tion. 

Organs of the Nervous 
System. — All the parts of 

the body are made to help 
one another, and to work 
together, by means of the 
nervous system. There are 
three principal organs of 
the nervous system : 1, the 
brain , situated in the top 
of the head; 2, the spinal cord , situated in the 
backbone; and 3, long strings of flesh, called nerves , 
which extend from the brain and spinal cord to all 
parts of the body. 

Organs for Voluntary Work. — There are two organs 
for doing voluntary work : 1, the brain, which does the 
work of thinking; 2, a large number of bundles of lean 
meat, called muscles , which produce motions. Stiff 



Diagram of a Complete Unit of 
Living Matter 

a, a cell; b, a blood tube which brings 
food and oxygen to the cell and car¬ 
ries away its waste matter; c, a nerve 
which carries messages between the 
cell and other parts of the body. 








ORGANS AND CELLS 


23 


rods and plates, called bones , support the soft flesh and 
assist the muscles to produce nearly all the voluntary 
movements of the body. 

Cells. — An organ is not like a lump of clay which is 
the same throughout its whole mass, but it is made 
up of microscopic units 
of living matter, called 
cells, which carry on all the 
work of the body. The 
cells are like separate ani¬ 
mals which form a per¬ 
fectly trained army under 
the control of master cells 
in the brain and spinal 
cord. They are supplied 
with food and oxygen by 
the blood ; and they work 
for the benefit of the whole 
body as they are ordered by the nervous system. A 
complete unit of living matter in the human body con¬ 
sists of three parts: 1, a cell; 2, a blood tube from 
which the cell gets its food and oxygen; and 3, a 
nerve which tells the cell when and how to act. 

Cells in Lower Animals and Plants. — All animals 
and plants are composed of cells. In the lowest forms 
of living beings each animal and plant is composed of 
a single cell. A common one-celled animal is called the 
slipper animal'cule, or parame'cium (-shf-um). It is 
microscopic in size, and is found in stagnant water. 



Parameciums 

(Magnified ioo times.) Each parame- 
cium is a complete animal consisting 
of a single cell. 





24 


ORGANS AND CELLS 


Place a handful of hay or dry grass in a jar of water, 
and leave the jar in a warm room. After two or 
three weeks the water will usually contain great num¬ 
bers of tiny white specks, each of which is a para- 
mecium. If you look at a drop of the water with a 

microscope, you can see the shape 
and structure of the animals as 
they move rapidly through the 
water. 

Collect some of the green, silky 
threads which float on still ponds, 
or grow on sticks and stones in the 
water. These threads are green 
plants called algce (al'je). Exam¬ 
ine a few of the plants under a 
microscope. You will see that 
each plant is a thread which con- 
Threads of Pond Alg^ sists of a single row of oblong cells 

joined end to end. 

All higher plants and higher 
animals, such as wheat or a cat, consist of masses 
of cells. 

Size and Shape of Cells. — The different kinds of 
cells in the human body vary in size and shape, but not 
one of them is large enough to be seen with the naked 
eye. If you scrape the skin with a knife, you will get 
a white powder which looks like flour. This powder 
consists of cells from the outer covering of the skin. If 
this powder is examined with a microscope, the separate 



Each thread consists of ob 
long cells joined end to end 





ORGANS AND CELLS 


25 


cells appear like flat scales. Cells scraped from the in¬ 
side of the cheek look nearly the same. These cells meas¬ 
ure from one five-hundredth-- 

to one one-thousandth of an 



inch across, and are extremely 
thin. 


A muscle cell is shaped like 
a string, and is about one 
five-hundredth of an inch in 
diameter and about one fiftieth 


of an inch in length. A blood Cells ^ ; er Inside of 


Cell is round and almost flat, (Magnified 100 times.) These are 



and measures about one 


three-thousandth of an inch across. If you put a bit 
of flesh under a microscope, you can tell from what 
organ it came by noticing the size, shape, and arrange¬ 
ment of its cells. 

How Cells Grow. — Most of the cells of a baby’s 
body are of the same size and shape as the cells of a 



Diagram of Cell Division 

After a cell reaches its full size, it may split into two parts, beginning with its nucleus. 


grown man, but there are not so many of them. A 
child does not grow by making the cells of its body 
larger, but by making their number greater. 






2 6 


ORGANS AND CELLS 


A cell consists of two parts: i, a soft jellylike sub¬ 
stance, which forms the greater part of the cell; and 
2, a darker bit of matter, called the nu'cleus , situated 
near the center of the cell. After a cell reaches full 
size, its nucleus may divide into two parts, and the rest 
of the cell then splits itself in half, forming two new 
cells, each containing half of the old nucleus. Thus a 
young cell is just half the size of a full-grown cell, 
but it is like a full-grown cell in all other respects. 




Connective Tissue Between 
Muscle Cells 


Bundles of Muscle Cells in 
Beefsteak 


(Magnified ioo times.) The connective (Natural size.) These bundles are cut 
tissue is white, and the muscle cells are across. The connective tissue is 
dark. white. 


Connective Tissue. — A group of cells that look 
and act alike is called a tissue (tish'u). The working 
cells of every organ are held in place by a tissue called 
connective tissue. These cells are small, and have long, 
slender arms which are tough and strong. These arms 
extend around and between the cells and hold them in 
place. If you examine the end of a piece of beefsteak, 
you will find a white network of tough connective 
tissue lying between red bundles of soft muscle cells. 







ORGANS AND CELLS 


2 7 


Some connective tissue is found in every part of the 
body. It forms the greater part of the skin. 

Epithelial Tissue. — The whole skin is covered with 
cells which are like soft scales. These are called epi¬ 
thelial (ep-i-the'li-al) cells, or e pit he'Hunt. They protect 
the soft and delicate flesh under them. 

Glands. — The skin is always moist with a liquid 
called the sweat , or perspiration. The sweat comes 



Diagram of a Gland 

a, cells of epithelium on the surface of an organ; b , cells of epithelium which line 
the tubes of the gland ; c, connective tissue which supports the gland cells. 

from pores, which are the openings of deep, narrow 
tubes extending into the skin. Each tube is lined with 
cells of epithelium, which extend down the tube from 
the surface of the skin. The use of the cells of epithe¬ 
lium in the tube is to form the sweat or perspiration out 
of material brought to them by the blood. 

A tube composed of cells of epithelium which form 
a substance out of the blood, is called a gland. The 














28 


ORGANS AND CELLS 


substance which a gland forms is called a secretion. 
Sweat glands are found in the skin on nearly every part 
of the body. 

The kidneys, liver, and pancreas are glands. They 
are composed of tubes of epithelium which either manu¬ 
facture substances for the use of the body, or take 
waste substances from the blood. 

The stomach and intestine contain glands which, se¬ 
crete digestive juices, that is, liquids which help to 
change food into liquid form. 

Nature of the Processes of Life. — Men used to 
think that the processes of life were carried on by what 
they called vital spirits , and that sickness was caused 
by evil spirits which made their home in the sick per¬ 
son’s body for a time. Now it is known that the work 
which goes on in most parts of the body is done by the 
same means and in the same manner as work is done 
in a workshop or laboratory. For example, food may 
be digested in a bottle in the same way as it is digested 
in the stomach. 

There are exact means of knowing the changes which 
take place in the body, both in health and in disease. 
The study of the living actions of the body has led to 
the discovery of the causes of most forms of sickness and 
of the means of keeping the body healthy. One does 
not need to be a physician in order to understand these 
changes ; and it is the duty of every person to learn how 
to run the machinery of his body and how to give it 
the proper care. 


ORGANS AND CELLS 


29 


QUESTIONS 

Name one great difference between bodies which are living and 
those which are lifeless. 

Name the two principal voluntary actions which take place in the 
body. 

Name some involuntary actions which take place in the body. 

What is an organ? 

Name the principal organs of digestion; of circulation; of ex¬ 
cretion ; of the nervous system ; of voluntary work ; of respiration. 

What are cells? 

1 

Describe a complete unit of living matter in the body. 

Give the sizes of several different kinds of cells. 

How do cells multiply in number? 

Describe an animal which consists of a single cell. 

Describe a plant in which cells may be readily seen. 

What is a tissue? 

What is connective tissue ? 

What is epithelial tissue? 

Describe a gland. 

What is a secretion f 

Name some glands. 

Name a living process which may be imitated in a laboratory. 

For the Teacher. — This chapter deals with two fundamental biological 
concepts: 

1. The division of labor in the various organs of the body. 

2. Units of living matter — the cells. 

Every piece of machinery made by man, such as a watch or a printing 
machine, consists of working units which may readily be seen. The units, 
or cells, of living things are microscopic in size, and yet they are remarkably 
alike in all forms of living things. The cells of the liver of a fish, for example, 
are strikingly like those of man. There is also a striking uniformity in the 
living actions of all cells. A study of single-celled animals illustrates the 
working of human cells. 

It is correct scientifically to consider the human body as made up of 
armies of living cells, all working for the common good under the control of 
governing cells in the central nervous system. 


CHAPTER III 


COMPOSITION OF THE BODY 

The Substances of the Body. — The substances of 
which the body is composed are constantly changing. 
Over a pound of flesh wears away each day, and new 
flesh is formed in its place. 

The body is composed of five different kinds of sub¬ 
stances. Their names are water, minerals, proteins 
(pro'te-inz), fats, and sugar. It is important for you to 
remember them and to understand what they are, for 
every act of the body produces a change in them. 

Water. — Water is the most abundant substance in 
the body. Three fourths of the weight of the flesh, 
and one fifth of the weight of bone, is water. It does 
not exist pure and alone in any part of the body, but 
it is always found mixed with other substances, which 
it softens and dissolves so that the processes of life 
can go on. 

Minerals. — If a person’s body were burned, about 
one twelfth of it would be left as ashes. The ashes are 
mineral substances which are mixed with the flesh, 
blood, and bone of every part of the body. The most 
abundant of the minerals is lime. Most of the lime is 
found in the bones, but some is found also in the flesh 


30 



COMPOSITION OF THE BODY 


3i 


and the blood. Salt, soda, potash, and iron are other 
important minerals which are always found in the 
body. 

Protein. — Protein is a substance which may be 
found in every living thing. An older name for it is 
albu'min. All life is carried on by means of it, and 
without it there can be no life. Growing cells consist 
principally of protein and water, with a little mineral 
matter. The protein in the body weighs about one 
eighth as much as the whole body. 

Pure protein is a solid substance which is like the 
dried white of an egg. It does not exist alone and in 
a pure form in any part of the body, but it is always 
found dissolved in water and mixed with a little mineral 
matter. When we speak of the protein of the body we 
mean a liquid or jellylike mixture of protein, water, 
and minerals. 

Liquid protein may be changed to a solid form by 
heat or other means. This change from a liquid to a 
solid form is called coagulation (ko-ag-u-la/shun). Ex¬ 
amples of the coagulation of protein are the hardening 
of the white of an egg when it is boiled, the curdling of 
milk when it sours, and the clotting of blood after it 
flows from the body. 

Fat. — About one tenth of the body consists of fat, 
which is like lard or tallow. Collections of fat lie under 
the skin, and between the bundles of muscles, and 
around many of the organs of the body. Fat itself is 
not a living substance, but what is called fat meat 



32 


COMPOSITION OF THE BODY 



consists of tiny pockets of living connective tissue 
filled with fat. The fat of a living body is not solid 
as it is in cold meat, but during life the heat of the 
body keeps it in a liquid form. 

The use of fat is to keep the body warm, and to fur¬ 
nish it with strength to work. When a person cannot 

eat food, his body uses up 
its own fat as food. It 
then loses weight and be¬ 
comes thin. Fat is food 
stored up to be used when 
the body cannot get other 
food. 

Sugar. — About eight 

ounces of substances which 
are like sugar are found in the liver and muscles of 
a grown person. Their use is to supply the body 
with heat and strength. 

Food.—The water, minerals, proteins, fats, and sugar 
of the body come from the food which is eaten. Our 
food consists of the same five kinds of substances. The 
body of a grown person takes about seven pounds of 
them daily, and it must give them off in nearly the 
same amounts, for its weight changes very slowly. 
But before getting rid of them, the body changes some 
of them by a process called oxida'tion , which is like 
the burning in a fire. 

Oxygen. — No person can live unless he takes air 
into his body several times each minute. The part of 


Fat Tissue 

(Magnified ioo times.) Fat is stored in 
pockets of connective tissue. 





COMPOSITION OF THE BODY 


33 


the air which the body uses is called oxygen. This 
substance forms about one fifth of the whole air. The 
quantity of oxygen which the body takes from the air 
each day weighs more than all its daily food except 
water. The oxygen passes through the body with 
the blood, and joins itself to food and flesh. The pro¬ 
cess by which oxygen is joined to another substance is 
called oxidation. 

Oxidation in a Fire. — A fire is an example of oxida¬ 
tion. Burning is the process by which oxygen is 
united with fuel, such as wood, coal, or oil. When wood 
burns, more than its 
own weight of oxygen 
unites with it quickly 
and forcibly. While 
the two substances are 



a great deal of heat. 

When the oxygen and 

the wood are joined Diagram of Oxidation in a Stove 
together, they become The same process goes on in the body, only 

smoke and ashes. much more sIowly ‘ 

Heat and Oxidation. — Oxidation in the body is the 
same kind of process as that which takes place when 
wood burns in a stove, but it takes place slowly and 
gently in the body. It produces the same quantity 
of heat that burning the food or flesh in a stove would 
have produced. The heat produced by oxidation keeps 
the body warm. 


OV. GEN. HYG. — 3 

























34 


COMPOSITION OF THE BODY 


Power from Oxidation. — Oxidation also gives the 
body power and strength to do work, just as the burn¬ 
ing of wood and coal supplies power to a steam engine. 
All the strength of the body to walk, or speak, or think, 
or to do anything else, comes from oxidation. When 
we say that the body wears itself out by working, we 
mean that it oxidizes its flesh and food, just as a loco¬ 
motive burns up coal when it runs. 

Worn-out Flesh. — The worn-out substances and 
waste matters of the body are mostly food and flesh 
which have been oxidized. They are composed of the 
same kinds of substances that are in the smoke and 
ashes of a fire. 

The protein, fat, and sugar of food and flesh are com¬ 
posed of the same simple substances as those of which 
wood and coal are mainly composed. The names of 
two of these substances are carbon and hydrogen (hl'dro- 
jen). The oxidation of these two substances supplies 
most of the heat and power of the body. 

Carbon Dioxide. — Carbon is usually a solid. A 
common form of it is charcoal. When oxygen unites 
with it, the two substances become a gas called carbon 
diox'ide , or carbonic acid. This is the same gas that 
is put into soda water to make it bubble and foam. 
Carbon dioxide is produced in fires by the oxidation 
of the carbon of the fuel, and is found in the smoke. 
It is also produced by the oxidation of the carbon in 
flesh and food, and is given off from the body by the 
lungs. 



COMPOSITION OF THE BODY 


35 


If you put one end of a tube into a glass of clear lime- 
water and blow through the other end, the carbon 
dioxide from your breath will turn the limewater milky. 
This is a proof of the presence of carbon dioxide. 

Manufacture of Water in the Body. — Hydrogen 
is a gas, and is one of the principal substances in the gas 
which is burned in houses. It is also abundant in wood, 
coal, and oil, and in a person’s flesh and food. When 
oxygen unites with hydrogen, the two gases become 
water. When a cold lamp chimney is put upon a 
lighted lamp, some of the water which is formed by the 
burning hydrogen of the oil may be seen on the inside of 
the chimney. Nearly a pint of water is formed each 
day in the body of a grown person by the oxidation 
of the hydrogen of food and flesh. 

Other Waste Matters of Oxidation. — Ni'trogen is a 
simple substance found in protein. When protein is oxi¬ 
dized, two substances are formed which contain the nitro¬ 
gen — u'rea and u’ric acid. These two substances 
are given off from the body by the skin and kidneys. 

When food or flesh is oxidized, its minerals are left 
behind, like the ashes of burned wood. They too are 
given off by the skin and kidneys. 

If the oxidation in the body is disturbed in any way, 
as by improper eating or breathing, the waste sub¬ 
stances will be far more harmful than the carbon diox¬ 
ide, urea, and uric acid which are naturally formed. 
These waste substances are the cause of much of the 
pain and weakness during most forms of sickness. 


3^ 


COMPOSITION OF THE BODY 


QUESTIONS 

Of what five kinds of substances is the body composed? What 
proportion of the body does each of these furnish ? 

Of what are the ashes of burned flesh composed ? 

Describe protein. Give an example of protein. 

How is fat stored in the body ? 

What is oxygen f What is oxidation ? 

Describe the process of burning in a fire. 

Compare oxidation in the body with a fire. 

Of what use is oxidation in the body ? 

Of what does worn-out flesh in the body consist ? 

What is carbon f What is hydrogen f 

What substance does each produce, when it is oxidized in the body ? 

What substances are formed by the oxidation of substances con¬ 
taining nitrogen? 

What are some of the effects of improper oxidation in the body ? 

For the Teacher. — The object of this chapter is twofold: 

1. To show the nature of the substances of which the body is composed. 

2. To show the nature of oxidation. 

The substances of which the body is composed are constantly being shed 
and new substances are formed into living flesh in their places. Almost the 
only substance which is not constantly renewed is that which composes the 
teeth. Many of the living actions of the body are like chemical actions which 
can be imitated in a laboratory. 

The essential process in the destruction of living flesh is that of oxidation, 
and is similar in most respects to that which takes place in a fire. The steps 
in the process of oxidation will be traced in more detail in the chapters on 
respiration, heat, and excretion. In this chapter teach the following topics: 

x. The substances which unite in the process of oxidation. 

2. The substances which are formed by the union. 

3. The heat and power which are developed by the process. 

The following outline will be helpful. Food and flesh are composed of four prin¬ 
cipal substances — 1, carbon; 2, hydrogen; 3, nitrogen; 4, minerals. Several 
ounces of oxygen enter the body daily and unite with the carbon, hydrogen, and 
nitrogen. 

Carbon -f oxygen = carbon dioxide 

Hydrogen + oxygen = water 

Nitrogen -f oxygen ( + carbon + hydrogen) = urea and uric acid 


CHAPTER IV 


DISEASE GERMS 

Infectious Diseases. — Diseases and disorders of 
the body are divided into two classes : 

1. Those which spread from the sick to the well, 
such as measles, scarlet fever, and colds. 

2. Those which do not spread, such as indigestion 
and broken bones. 

Diseases which are caught by one person from another 
are called infectious diseases. They are also called 
catching , or contagious , or communicable diseases. They 
are caused by living plants or animals, called disease 
germs , which grow in the body. When a disease is 
caught, a few of its germs enter the body and multiply 
to countless millions. More than half of the deaths 
which occur before old age are caused by infectious dis¬ 
eases. Nearly all fevers and colds are caused by 
disease germs. 

Decay. — Infectious diseases in living things are 
like the processes of decay in lifeless matter. A living 
thing preserves itself; but after it dies, it usually be¬ 
comes soft and goes to pieces, unless great care is taken 
to preserve it. The natural process of destruction is 
called decay , or rotting. 


37 


38 


DISEASE GERMS 


The final result of decay is the oxidation of dead 
matter and the formation of the same substances that 
would have been formed if the decaying matter had 
been burned. For example, the body of a dead animal 
that is buried in the ground becomes oxidized and 
changed to gases and ashes. When the process of de¬ 
cay is complete, the oxidized products are in such a 
form that plants can use them as food, and can build 
the particles again into living forms. The fertilizers 
which farmers spread upon their land consist princi¬ 
pally of decaying substances. Decay is as necessary as 
growth, for if dead animals and plants did not decay, 

their remains would 
soon cover the 
whole earth. 

The processes of 
decay are caused 
by three groups of 
living things, called 
molds , yeasts , and 
bacte'ria. 

Molds. — Com¬ 
mon molds produce 
a furry or wooly 
coating on the 
substances on which they grow; but the fur on the 
surface is only the fruit of the mold plants. The 
greater part of a mold plant consists of slender threads 
which grow beneath the surface of the substance, and 






DISEASE GERMS 


39 


are so small that the separate threads can scarcely be 
seen with the naked eye. Under a microscope the 
threads appear as long cells joined end to end into 
strings. Mold threads multiply rapidly, and cause de¬ 
cay in substances in which they grow. 

Mold Spores. — Full-grown mold plants send up 
fruit stalks above the surface. Each stalk is tipped 
with a tiny knob 
which is filled with 
tiny balls, called 
spores. Each spore 
is a kind of seed 
which may grow 
and produce a mold 
plant. The spores 
float away in the 
air and grow on 
substances on which 
they fall. They are 
scattered everywhere, and so molds are found wherever 
there is the proper soil on which they can grow. 
Molds have important effects on the health and com¬ 
fort of persons, for they cause food to spoil and wood 
to decay ; and wherever they grow, disease germs may 
usually grow also. 

Yeast. — A common process which is like decay is 
that caused by yeast, and is called fermenta'tion. 
Yeast plants are small, oval cells. A yeast cake that 
is used in making bread consists of millions of dried 



Photograph of Mold Stalks and Spore 

Cases 

(Magnified io times.) 







40 


DISEASE GERMS 


yeast plants mixed with flour or meal. When the 
yeast cake is placed in water which contains sugar, the 
cells grow rapidly and new cells spring from the sides 
of the old ones, like buds from a twig. In this way yeast 
plants increase in numbers with great rapidity. Grow¬ 
ing yeast plants change sugar to alcohol and carbon 
dioxide, or carbonic acid gas. The gas rises through 
the liquid in bubbles which look like bubbles of steam 

in boiling water. It is for this 
reason that the process is called 
fermentation, from the Latin 
word which means boiling. 

Yeast cells may remain alive 
after they are dried. They 



Yeast Plants 

Diagram of growing yeast cells, may fl oat i n the air as dust, 
showing the buds which spring J 

from the full-grown cells. (Mag- and may grow again when they 

nified 500 times.) . . . 

fall into fruit juice or other 
liquid which contains sugar. Fruit juice usually fer¬ 
ments within a few hours or days because of the yeasts 
which fall into it. 

Bacteria. — The most common forms of decay are 
caused by tiny living things called bacteria , which are 
the smallest living things that are known. When 
they are examined under a powerful microscope, 
most of them appear like the dots and dashes on a 
printed page. 

How to See Bacteria. — An easy way to find bacteria 
is to soak a handful of hay in a bottle of water. After 
a few days examine a drop of the water with a micro- 




DISEASE GERMS 


4i 


scope, using its greatest magnifying power. You will 
see great numbers of bacteria that appear like faint 
dots and dashes in constant motion. 

How Bacteria Grow. — Bacteria increase in number 
by the simple process of each one dividing itself into 
two bacteria, just as if it had been broken in two. Each 
of the two is as complete and separate a bacterium as 
the single plant was before it became divided. Within 
an hour each of the two 
may reach its full size 
and may itself divide 
into two, thus making 
four bacteria. Each of 
the four may divide 
within another hour, 
making eight. If this 
goes on for twenty-four 
hours, there will be sixteen millions of bacteria in place 
of only one, and yet they are so small that the whole of 
them would form a lump no larger than a small grain 
of sand. At the end of two days the bacteria would 
multiply to two hundred and fifty-six millions of mil¬ 
lions, and would fill a pint measure. At the end of 
three days there would be enough bacteria to load an 
ocean steamship. Bacteria often multiply at this rate 
for a few hours, in substances which decay or 
putrefy readily, but they soon use up all the food 
which they can reach, and their further growth is then 
impossible. 



Bacteria in Hay Water 

(Magnified 1000 times.) Bacteria are the 
principal causes of decay. 





42 


DISEASE GERMS 


Where Bacteria are Found. — Since bacteria multi¬ 
ply with great rapidity, they are the most abundant of 
all living things. Countless millions are found in all 
kinds of decaying substances, and in the soil. Water 
usually contains a few of them, and every object is 
sprinkled with them. About a thousand bacteria are 
found in each drop of milk when it is fresh and clean, 
but a million may sometimes be found in each drop 
after it has stood for a day in an ordinary pantry. 

Of all living things, bacteria are the hardest to kill. 
Drying or freezing does not kill most of them, but only 
stops their growth until they become wet and warm 
again. When dried, they are often blown away by the 
wind, and so bacteria are found in most dust, and on 
everything on which dust falls. 

Canning Food. — The processes of decay and of fer¬ 
mentation, as in the spoiling of food, are catching or in¬ 
fectious. A decaying apple will cause decay to begin 
in another apple which it touches ; and a yeast cake will 
cause fermentation to start in bread dough or fruit 
juice into which the yeast cake is put. 

A food or other substance will not decay or ferment 
or turn sour if there are no living molds, yeasts, or 
bacteria in it. The process of preserving food by can¬ 
ning consists of boiling the food so as to kill all living 
things in it, and sealing the food in air-tight cans so 
that no more mold spores, yeasts, or bacteria can enter 
it. Food canned in this way will remain fresh for 
months or years. 


DISEASE GERMS 


43 


Canned food often spoils because of failure to boil the 
jars and covers in order to kill the molds on them. A 
good way to can fruit is to put it into jars and put the 
covers on loosely. Then boil the jars and fruit to¬ 
gether, and, lastly, fasten the covers on tightly. 



Food Preserved by Canning 

Heating kills the molds, yeasts, and bacteria, and sealing the cans prevents more 

from entering the food. 


Useful Bacteria. — Many kinds of bacteria produce 
substances which are pleasant to the taste or smell, 
or which are useful to man. Bacteria change cider 
to vinegar. They are necessary in making butter, 
for butter made from cream which contains no bac¬ 
teria would taste about like lard. Farmers depend on 
bacteria to cause substances to decay and enrich the 
soil, and cities often depend on bacteria of decay to 
destroy their sewage. Over a thousand kinds of 









44 


DISEASE GERMS 


bacteria are known, and nearly all of them are useful 
to man. 

Bacteria in the Body. — Many kinds of bacteria 
which produce offensive decay often grow on the skin. 
In the mouth, bits of food, dead skin, and the moisture 
of saliva form a good soil in which many kinds of bac¬ 
teria may flourish and cause decay and a bad breath. 
Bacteria are the cause of decay in teeth. They may 
grow in the dead scales of a dirty skin and cause the 
bad odors of an unwashed body. They may grow 

abundantly in the 
intestine, and be 
the cause of many 
forms of indigestion. 

A few kinds of 
bacteria may grow 
in living flesh. 

Typhoid Bacteria These are the causes 

(Magnified 2000 times.) A few of these germs niOSt kinds of 

taken into the body grow and multiply, and pro¬ 
duce severe sickness. infectious diseases. 

List of Infectious Diseases. — The common diseases 
which persons may catch from others who have the 
same diseases number about twenty. Among those of 
which bacteria have been proved to be the cause are 
diphtheria (dif-the'ri-a), typhoid fever, tuberculosis, 
grippe, pneumonia (nu-mo'ni-a), lockjaw, erysipelas 
(er-i-sip'e-las), and most kinds of tonsillitis, colds, and 
sore throat. Pimples, boils, and all other kinds of 
sores which give off a creamy matter are often called 



t» ~ 1 





DISEASE GERMS 


45 


blood poisoning, but they are all caused by bacteria 
growing in the flesh. 

Other examples of infectious diseases are mumps and 
whooping cough, and also those diseases in which the 
skin becomes spotted or broken out, such as measles, 
German measles, scarlet fever, smallpox, and chicken 
pox. They resemble the 
diseases whose cause has 
been proved to be bacteria. 

Other Kinds of Disease 
Germs. — A few kinds 
of infectious diseases are 
caused by microscopic ani¬ 
mals which grow in the 
blood. Malaria is caused 
by a microscopic animal 
which one kind of mos¬ 
quito leaves under a per¬ 
son’s skin when it sucks 
his blood. Hydropho'bia is 
caused by microscopic animals which grow in the brain. 

Where Disease Germs are Found. — Germs of dis¬ 
ease do not grow naturally in the soil, or water, or air, 
or food. Nearly all kinds grow only in the bodies of 
sick persons or animals, but they may stay alive after 
they have left the bodies of the persons or animals in 
which they have grown. If a person has an infectious 
disease, it is because he has received living germs from 
some one who was sick before he was. Every person 


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X 


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- rwfC 





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The Skin in Chicken Pox 

The germs in chicken pox, growing in 
the body, cause the skin to “break 
out.” 




46 


DISEASE GERMS 


who has an infectious disease is dangerous to others 
around him, unless great care is taken to kill all the 
germs which come from his body. 

When a person has an infectious disease, some of the 
germs may leave his body from sores and wounds, if 
there are any on the skin ; but very few germs leave the 
skin when it is clean and sound. Nearly all the germs 
which leave the body pass off either from the nose, or 
mouth, or from the intestine, or from the kidneys. If 
every sick person would guard these four gateways of 
his body, few disease germs could escape alive, and 
soon no one could catch an infectious disease, for all the 
germs would be dead. 

Cleanliness. — If disease germs are not caught and 
killed as soon as they leave the body, they may remain 
alive for some time. They are found on everything 
which has been soiled by those who are sick with in¬ 
fectious diseases. They are found in dirt, filth, sewage, 
and garbage; in the dust and foul air of houses and 
meeting places; on dirty handkerchiefs, towels, bed¬ 
clothes, and soiled garments; and on forks, spoons, 
dishes, and other articles which have been used by the 
sick. The prevention of diseases depends largely upon 
cleanliness. 

Cleanliness does not mean something hard and dif¬ 
ficult which only a doctor can understand, but simply 
keeping clean in a way that a good housekeeper under¬ 
stands. It also means keeping back yards and kitchens 
clean and neat. 



DISEASE GERMS 


47 


QUESTIONS 

What are infectious diseases? Name several. 

By what are infectious diseases caused ? 

What are molds? What are spores? 

On which part of a mold plant do the spores grow? 

Why does a piece of bread often become moldy a few days after 
it is cut? 

What is yeast ? What is fermentation ? 

What substances are produced by yeasts? 

What are bacteria? 

How large are bacteria? 

What do bacteria look like ? 

Where may bacteria be found? 

How do bacteria grow and multiply ? 

What have bacteria to do with decay or rotting? 

Of what use is decay? 

Name some other uses of bacteria. 

W T hy does food keep fresh when it is properly canned? 

Where do the bacteria of infectious diseases grow ? 

From what part of a sick person’s body are disease germs given off? 

Where are disease germs likely to be found outside of a human 
body? 

What has cleanliness to do with preventing the spread of diseases? 

For the Teacher. — The object of this chapter is to show the nature of the 
living organisms which produce most of the processes of decay and of infectious 
diseases. The concept of bacteria is at the basis of most phases of modern 
sanitation. It is introduced early in this study of hygiene in order to afford a 
basis for understanding the reasons for the hygienic care of the body. Among 
the topics to be taught are: 

1. The three groups of microscopic organisms which produce the actions 
of decay, fermentation, and infectious diseases. 

2. The infectious nature of decay and communicable disease. 

3. Where disease germs are produced; how they are spread; how they 
enter the bodies of well persons; and how they may be kept out of the body. 

4. The nature of the process of canning food. 

5. The human origin of infectious diseases. Dirt, decaying substances, and 
impure food do not produce disease germs; they may carry the germs from the 
sick to well persons. 


CHAPTER V 


DEPARTMENT OF HEALTH 

Need of a Health Department. — The prevention of 
disease is the duty of every individual citizen, and also of 
a branch of government called the department of health. 
An infectious disease, like a fire, may spread through 
a community in a great wave, called an epidemic (see 
p. 13). It is the duty of every person to respect the 
property, the rights, and the health of others, and to 
cooperate in keeping diseases from spreading. But 
many persons are careless and do not put themselves 
to the trouble of protecting others; and many are 
ignorant and do not know how to prevent disease 
germs from spreading. There is need, therefore, that 
one branch of government should be a department of 
health in order to direct the work of preventing diseases. 
Departments of health are organized in states, counties, 
cities, villages, and townships. 

A department of health does not relieve any citizen 
of his duties, but it adds to his responsibilities by re¬ 
minding him of his duties and compelling him to do 
them. The principal work of preventing diseases must 
be done by individual citizens. A department of health 
is like a good teacher in a school in which each pupil 

48 



DEPARTMENT OF HEALTH 


49 


tries his best to learn and to obey the rules of order and 
work. The success of the work of a department of 
health depends upon each citizen’s efforts to obey the 
health laws and to follow the rules for the prevention 
of diseases. 

History. — The modern work of preventing infectious 
diseases in the United States began in the years be¬ 
tween 1830 and 1840, when the people of the larger 
cities began to put plumbing into their homes, and to 
build sewers and modern waterworks. Before that 
time people thought the soil, air, and water were natur¬ 
ally poisonous in some places and healthful in others. 
It was then found that diseases spread in places which 
had been healthful, and that wells which had produced 
wholesome water began to spread diseases. The cause 
of this change to unhealthfulness was found to be ac¬ 
cumulations of sewage, garbage, rubbish, dirt, and 
filth which had resulted from overcrowding and the 
lack of means of carrying away the waste substances. 
Men believed that diseases would cease if homes and 
yards and streets were made as clean as the earth 
naturally is in uninhabited places; and so they organ¬ 
ized departments of health, whose principal duties were 
to remove sewage, garbage, and other decaying sub¬ 
stances, and to make everything clean. The result 
was a marked reduction in intestinal diseases, for they 
were often spread by sewage and water; but other 
kinds of diseases remained as prevalent as ever. 

The prevention of diseases between 1830 and 1880 


OV. GEN. HYG.—4 



50 


DEPARTMENT OF HEALTH 


was founded on the belief that any decaying substance 
could produce a disease. But between the years 1880 
and 1890 disease germs were studied and their origin 





npmups p/cs 


'/ropups vptsp. 





55 


t \ 


r 1/ 




Old and New Theories about the Cause of Infectious Diseases 


It was formerly thought that any decaying substance could produce a disease. 
Now it is known that disease germs come from sick persons, but may be carried from 
them to other persons by means of sewage, or garbage, or dirt of human origin. 


traced, and it was found that dirt and decaying sub¬ 
stances did not contain disease germs, and did not 
produce a disease, unless they contained germs which 
came from a diseased person (or, in a few cases, from 
a diseased animal). It was also discovered that dis¬ 
eased persons were spreaders of diseases, and that 












DEPARTMENT OF HEALTH 


5i 


decaying household waste was only one means by 
which disease germs were spread from sick to well 
persons. Departments of health then extended the 
range of their duties, and now the principal part of 
their work is to find and control the persons who pro¬ 
duce disease germs. But they also continue the work 
of sewage disposal, water purification, and cleanliness 
as actively as ever. 

Public Health Work. — The care of the health of the 
people is the work of physicians, and is done along two 
lines: 

1. Private practice. 

2. Public health work. 

Private practice consists principally in treating sick 
persons to whom the physicians are called. The prin¬ 
cipal work of a physician in private practice is to cure 
persons after they have become sick. Public health 
work consists in preventing sickness. It is done largely 
by physicians and nurses who are employed by health 
departments. The physicians of the departments deal 
principally with infectious diseases. They help private 
physicians to recognize diseases, and they assist in 
curing sickness when they are asked; but their great 
work is to prevent diseases from spreading. In this 
work it is the duty of every private physician to assist. 
The laws of most states require every physician to re¬ 
port to the health department the name and address 
of every person whom he treats for any infectious dis¬ 
ease which the department may require to be reported. 


52 


DEPARTMENT OF HEALTH 


Among such diseases are diphtheria, scarlet fever, and 
typhoid fever. 

Methods of Public Health Work. — A department 
of health has two methods of work : 

1. Compulsion. 

2. Advice and persuasion. 

States, counties, cities, villages, and towns have 
health laws for the control of diseases; and their de- 



Compulsion Persuasion and Education 

The two methods of doing public health work. 


partments of health have the power to compel all per¬ 
sons to obey the laws, and to arrest and punish those 
who disobey them. The power to compel obedience 
is called police power. Departments of health seldom 
use this power, but they act principally by means 
of advice and persuasion. A law represents the wishes 
of the greater part of the people of a community. If 















































































DEPARTMENT OF HEALTH 


53 


the people will not support a health department when 
it tries to compel obedience, the department can do 
little. But physicians and nurses of health departments 
can usually persuade people to observe health laws, and 
the people are willing to obey them when they under¬ 
stand their meaning and necessity. Ignorance is the 
principal reason for disobeying health laws. A good 
public health worker must be first of all a good 
teacher in health matters. 

Public Health Education. — Education in health 
matters is carried on along two lines: 

1. Individual instruction. 

2. Public teaching. 

When a physician or other officer of a department of 
health calls on a person, he explains the reasons for the 
orders which he gives. Instructions in disease pre¬ 
vention are given to the family of every person on 
whom the officer calls on account of an infectious 
disease; every person on whom a call is made for dis¬ 
obeying a health rule is taught how he shall act; 
and inspectors give out information regarding the care 
of cesspools, covering food, and other health matters. 

The officers of departments of health also make re¬ 
ports about their work and publish pamphlets and news 
items informing the people about infectious diseases, 
and giving them warning and instruction when a dis¬ 
ease appears in a town. One of the principal lines of 
work of a good department of health is that of public 
health education. 


54 


DEPARTMENT OF HEALTH 


Department of Health. — There is a health depart¬ 
ment in nearly every state, and other boards or officers 
for counties, or cities, or villages, or towns. Every 
citizen is directly under some department of health to 
whom he may complain and from whom he may seek 
advice. A department of health usually consists of 
a board of health, and a health officer and his as¬ 
sistants. 

A board of health, by whatever name it may be 
called, is the governing body of a health department. 
Some of its more important duties are: 

1. To appoint the officers, inspectors, clerks, and 
other persons employed by the department. 

2. To handle the money of the department. 

3. To make rules and regulations for the protection 
of health. 

The health officer is usually a physician. He man¬ 
ages the health work of the department. Some of his 
more important duties are : 

1. To receive and act upon reports which physicians 
and others make regarding persons who have infectious 
diseases. 

2. To investigate complaints regarding unhealthful 
conditions and see that the conditions are corrected. 

3. To be a leader in educating people in health 
matters. 

The larger departments of health also employ nurses, 
inspectors, and clerks to assist the health officer and 
keep the records of the department. The Health De- 



DEPARTMENT OF HEALTH 


55 


partment of the city of New York employs over two 
thousand persons. 

Results of Public Health Work. — The people of 
the United States and other highly civilized countries 
have received more benefit from public health work than 
from almost any other source. Among the results are : 

1. A death rate less than half of that of a centurv 
ago (p. 12). 

2. Longer life for most persons (p. 12). 

3. Less disease, suffering, and loss of time from 
sickness. Cholera, typhus fever, and plague are rare 
diseases; smallpox has been almost suppressed; and 
typhoid has been reduced to one tenth of its former 
prevalence. 

Future Public Health Work. — Many diseases still 
remain to be overcome. Tuberculosis, pneumonia, 
colds, and other diseases of the lungs and air tubes 
remain unconquered, but public health workers are 
constantly making discoveries which promise future 
results even greater than those of the past. 

The public health work of the past has been princi¬ 
pally that of preventing diseases. It was formerly sup¬ 
posed that the human body would grow up strong and 
vigorous if there was no sickness or disease. But many 
children are born with defects which prevent their 
growth, and many parents are ignorant and allow their 
children to form bad habits of eating, sleeping, and 
doing other acts which prevent them from living lives 
of action and vigor. The public schools have already 



56 


DEPARTMENT OF HEALTH 


begun the work of examining pupils, and are not only 
correcting their defects and bad health habits but also 
establishing good health habits among them. Public 
health work of the future will grow beyond merely es¬ 
caping sickness, and will include the promotion of living 
with perfect strength and vigor of both body and mind. 

Health of Mind and Body. — Men of olden times 
thought that the body was opposed to the mind. They 
used to starve themselves and torture their flesh in 
trying to weaken their bodies in order to free their 
minds and spirits. It is now known that the only per¬ 
sons whose minds are free are those whose bodies are 
in such perfect health that their minds are not disturbed 
by any unpleasant bodily feelings. The first thing to 
do in helping the mind of any troubled person is to make 
his body comfortable and healthy. One of the great 
duties of a government is to provide the means by 
which each citizen may preserve a healthy mind in a 
healthy body. 


QUESTIONS 

Give some reasons for the need of departments of health. 

What are the duties of every citizen in preventing disease ? 

How may a citizen help the health department? 

What kind of work was first done by health departments ? What 
is the principal kind of work that is done at present ? 

What is the difference between the practice of a private physician 
and the work of one employed by a department of health ? 

Why is better public health work accomplished by education than 
by compulsion? 

Describe some means of educating the people in health matters. 



DEPARTMENT OF HEALTH 


57 


Of what does a department of health consist ? 

What are the duties of a board of health? of a health officer? 
What is the name and address of the health officer to whom you 
would make a complaint ? 


For the Teacher. — Make a direct application of this chapter to the local 
health department of the community in which your school is located. Who 
is the health officer? What is his address? his telephone number? 

Go to your health officer and get a set of the blanks on which cases of con¬ 
tagious disease are reported ; and also a set of the descriptive pamphlets which 
he gives to the cases. Many states supply these to the health officers. 

Does the health officer keep a record of all cases of contagious diseases that 
occur in your community? How many occurred during the past year? If a 
pupil in your school broke out with scarlet fever, how would you inform the 
health officer about the case? What would your health officer do to quaran¬ 
tine, or isolate, or otherwise control the case? 

If your health officer should fail to do his duty, who is the higher officer to 
whom you would make complaint ? (It may be his board of health, or a county 
health officer, or a state department of health. The organization of health 
departments varies greatly in the several states.) 

Are health articles published in your local papers? Are health lectures 
ever given in your community? health pictures shown? health exhibits 
held ? 

Ask your health officer to come to your school and give a talk to the pupils. 
Merely to see the health officer will make him a real personage to them. 
Try to make the pupils familiar with their own health department. Without 
criticizing, show how the public health service could be brought up to the 
standard of that in the most progressive communities. 

Emphasize the fact that each individual has a personal responsibility to care 
for his own health, and especially to form good health habits of daily living, and 
to do health chores in the routine daily care of his body. Show that the protec¬ 
tion of one’s own health requires that each person also shall do health chores in 
order to protect the health of other persons. Personal hygiene merges into civic 
hygiene. 


CHAPTER VI 


STIMULANTS AND NARCOTICS 

Appetites. — Cats, dogs, and other animals are 
able to live healthy lives because they are born with 
appetites and feelings which they follow in whatever 
they do. Their feelings of hunger and thirst, of pain 
and fatigue, of joy and pleasure, and of anger and fear, 
are some of the guides by which they live and act. 

Men have the same kind of appetites and feelings 
that lower animals have, and they take these feelings 
as their guides in what they do. But they also have 
their thoughts to guide them. An animal does not 
think, but it tries to satisfy its appetite as soon as it 
feels a desire for something. Men can think what will 
happen if they should satisfy an appetite, and they can 
judge whether or not it is best to do what they feel like 
doing. They live by means of their thoughts, as well 
as their feelings. 

Pleasure of an Appetite. — Satisfying an appetite 
gives pleasure and leads us to supply the needs of the 
body. If eating were a painful duty, many persons 
would starve to death rather than take food. But eat¬ 
ing is a great pleasure, and many persons eat too much 

58 



STIMULANTS AND NARCOTICS 


59 


because they think of the pleasure of eating, and forget 
the needs of their bodies. Appetites are not always 
sure guides, for they may be false and harmful. 

False Appetites. — Some persons have appetites for 
things which are not good for them. Many harmful 
substances seem to give pleasure at first, but they cause 
sickness a few hours or days after they have been 
taken. Some of these things are alcohol, tobacco, and 
opium. Many persons have appetites for them, and 
take them when they know their danger. These 
appetites are false, but they are often more powerful 
than the appetites which are true and useful. Men 
often yield to false appetites because they think only 
of their present pleasures. 

Intemperance. — A person who eats too much is in¬ 
temperate in his eating ; but intemperance usually means 
satisfying a false appetite for drinks which contain al¬ 
cohol, and which are often called strong drinks. Men 
sometimes take a strong drink because they have an 
appetite for it, and do not stop to think of the harm 
that it will do. 

There are many kinds of strong drink, but all of them 
contain a substance called alcohol. They are manu¬ 
factured from liquids which contain sugar, and are 
made by changing the sugar to alcohol. This change 
is produced by means of yeast (p. 40). 

Fermentation. — The juice which is pressed from 
sweet fruit, such as grapes, contains sugar, coloring mat¬ 
ter, and flavorings. After it has stood for a few hours, 



6o 


STIMULANTS AND NARCOTICS 


it begins to ferment. The fermentation is caused by 
yeast plants which fall into the juice from the air. 
The yeast changes the sugar to alcohol, and the juice 
is then an intoxicating liquor, called wine. 

Fresh fruit juice is a wholesome food and drink, for 
it is fruit from which the skins and tough parts of the 
pulp have been taken. If the juice is heated and put 
into sealed cans or bottles, it may be kept for months 
without fermenting, just as canned food is kept (p. 42). 
In this way fresh grape juice, called unfermented wine, 
is preserved. 

The juice of apples is called cider. This juice, if not 
preserved, begins to ferment within a few hours after 
it is pressed out, and cider which is only a few days old 
may contain enough alcohol to be harmful. 

Other kinds of strong drink, such as beer and whisky, 
are made from sprouted grain in which part of the starch 
has been changed to sugar. Many patent medicines 
and so-called tonics contain a considerable amount of 
alcohol and are dangerous to health. 

Vinegar. — If a fruit juice contains only a little sugar, 
it will become sour when it ferments. This is because 
bacteria grow in the juice with the yeast, and change its 
alcohol to a sour substance called acetic (a-se'tik) acid. 
After cider has fermented for some weeks, all of its 
alcohol becomes acetic acid, and the liquid is then 
called vinegar , from two Latin words meaning sour 
wine. A great deal of vinegar is made from the juice 
of grapes and apples. 



STIMULANTS AND NARCOTICS 


61 


Uses of Alcohol. — Pure alcohol is made by a process 
called distillation , in which the vapor from a boiling 
fermented liquor is caught and condensed. Alcohol is 
a liquid which looks like water. It will dissolve many 
substances which water will not dissolve, and for this 
reason it is largely used in manufacturing. Meat 
placed in it will not decay, and so it is used in schools 
and colleges for preserving specimens. It will burn 
with a hot flame without smoke, and so it is often 
used for heating and cooking. If mixed with air, it 
will explode, and so it is sometimes used in engines in 
place of gasoline. 

There are two kinds of alcohol in common use. One 
kind is made from wood, for use in manufacturing; 
this is very poisonous if used in drink. The other kind 
of alcohol is made from grain, and is the kind that is 
used in strong drinks. 

Drunkenness. — Strong drink produces two kinds 
of harmful effects on those who take it. One kind of 
harm is that which comes on within a few moments 
after the drink is taken. This effect is called drunk¬ 
enness, or intoxication. Drunkenness is a severe sick¬ 
ness of both the body and the mind. It harms a 
person as any other form of sickness will. 

The other kind of harmful effect which is produced 
by alcoholic drinks is a slow poisoning of the whole 
body and mind. This effect may come from taking 
small quantities of drink often, even though the person 
does not get drunk. 



62 


STIMULANTS AND NARCOTICS 


Alcohol a Stimulant. — Alcohol acts like a whip to 
the mind and the body. The old Romans called a 
whip a stim'ulus, and for this reason alcohol is called a 
stimulant. A whip does not make a person or an animal 
strong. There are far better ways of getting a man to 
work than by driving him with a whip, or with a stim¬ 
ulant. 

Alcohol rouses a person up, and he may then think 
that his strength is increased because he feels like 
doing something. But the drink really disturbs him 
in his work, just as whipping a boy in school every few 
minutes would disturb him in getting his lessons. A 
difference between a whipping in school and a stimu¬ 
lation with alcohol is that the whipping causes pain 
at once; but alcohol dulls the mind, and prevents the 
harm from being felt until afterward. This is the 
great danger from taking alcohol, for it deceives the 
drinker, and makes him think that he is being helped 
when he is really being harmed. 

Alcohol a Narcotic. — The mind of a man who is 
stimulated with alcohol is benumbed and cannot act 
right, even though it tries to do so. For this reason 
alcohol is called a narcot'ic , from a Greek word meaning 
to make numb. 

Prohibition. — The use of alcoholic liquors as drinks 
and medicines is a relic of early times, when men drank 
because it was the custom to do so, and when physicians 
gave alcohol as a medicine because of its quick effect. 
But when the effects of alcoholic drinks were tested 



STIMULANTS AND NARCOTICS 


63 


and measured accurately, they were found to be over¬ 
whelmingly bad. The United States, therefore, 
adopted the Eighteenth Amendment to the Constitu¬ 
tion in 1919. This amendment reads as follows: 

“ Section i : After one year from the ratification of 
this article, the manufacture, sale, or transportation 
of intoxicating liquors within, the importation thereof 
into, or the exportation thereof from the United States 
and all territory subject to the jurisdiction thereof, 
for beverage purposes, is hereby prohibited. 

“ Section 2 : The Congress and the several States 
shall have concurrent power to enforce this article by 
appropriate legislation.” 

The Eighteenth Amendment is now a part of the 
Constitution of the United States, and is as binding as 
any other part of the highest law of the land. 

The Congress of the United States has defined in¬ 
toxicating liquors to be those which contain one half 
of one per cent, or more, of alcohol by volume. 

Tobacco. — Tobacco is a plant which grows about 
as tall as a man. It has a central stalk which bears 
large, broad leaves. The leaves are gathered and dried, 
and then manufactured into smoking tobacco, chewing 
tobacco, and snuff. 

Nicotine. — Tobacco contains a substance called 
nicotine (mk'o-tm), which is a narcotic and a powerful 
poison. Two or three drops of pure nicotine would 
make a man dangerously sick. The quantity of to¬ 
bacco which is usually taken at once contains enough 



64 STIMULANTS AND NARCOTICS 

nicotine to kill a man, if all of it should be swallowed 
at one time. The reason why those who use tobacco 
are not killed by it is that they do not swallow much 
of the nicotine. 

Effects of Tobacco. — Tobacco produces a quick 
form of poisoning, and a slow form. The quick form 


Tobacco Plants 

1,500,000 acres in the United States are used for raising tobacco. 

of poisoning is a feeling of stomach sickness, with 
paleness and weakness. Most persons are made sick 
when they first try to smoke or chew. The body 
may become somewhat used to the poisonous effects 
of tobacco, but even the greatest smokers and chewers 
become sick when they take a little more than usual 
at one time. 






STIMULANTS AND NARCOTICS 


65 


When tobacco is used day after day, it produces a 
slow poisoning of the heart, lungs, muscles, eyes, and 
other parts of the body. These effects will be men¬ 
tioned when the separate organs are studied. 

Tobacco and Young Persons. — Tobacco has a far 
greater poisonous effect on young persons than on those 
who are grown. Many boys think that while they are! 
smoking they look like grown-up persons ; but smoking 
prevents them from growing up strong and healthy. 
After a person has got his growth, he can stand an 
amount of poisoning which would make a young per¬ 
son dangerously sick. 

Cigarettes. — Many young persons suppose that cig¬ 
arettes are only slightly poisonous. A cigarette is not 
so poisonous as a large cigar, or a pipeful of tobacco, 
because it is smaller. But the small quantity of nico¬ 
tine that is in a cigarette is more poisonous to a boy 
than the large amount of nicotine in a cigar or pipe is 
to a grown man. The use of cigarettes by boys is so 
dangerous that many states have laws forbidding their 
sale to those who are under eighteen years of age. 

Opium. — The dried juice of poppy plants is a 
gummy substance called o'pium. It contains morphine 
(mor'fm) and other poisonous substances. Opium 
is a valuable drug which is used in medicine to ease 
pain and to produce sleep. It is a strong narcotic 
poison, and its use is so dangerous that only skilled 
physicians know how to give it safely. Yet many 
persons who begin to take it for pain form a habit of its 


OV. GEN. HYG. — 5 




66 


STIMULANTS AND NARCOTICS 


use, just as men form a habit of using alcohol or tobacco. 
The opium habit is extremely dangerous, and those 
who form it seldom live more than a few years. 

Many lives are lost each year because the sick take 
opium or morphine, and then suppose that they are 
out of danger because they feel no pain. A pain is 
a valuable sign of sickness and danger. If you have a 
bad pain and it is taken away by the use of opium or 
morphine, you need a good nurse or doctor to look after 
you, for the narcotic dulls your mind and feelings, and 
you cannot judge for yourself how ill you are. 

Headache Cures. — Many medicines which are sold 
for the cure of headache contain drugs which make 
the heart extremely weak. These drugs do not remove 
the cause of the headache, and their use is dangerous. 

Drugs and Health. — Many persons suppose that 
some drugs will make them strong, that some will 
drive away diseases, and that others will make their 
complexions fair. This is not so. All drugs which 
have much effect on the body are poisons, and only 
trained doctors know how to use them. But giving 
drugs is only a small part of what a doctor does to cure 
a sick person. He tries to remove the cause of the 
sickness. For example, if a person is sick because he is 
tired from overwork, the doctor does not give him drugs, 
but tells him how to work and rest. In the prevention 
and cure of sickness a knowledge of the use of drugs is 
of far less value than a knowledge of hygiene and of 
right living. 


STIMULANTS AND NARCOTICS 


67 


QUESTIONS 

Of what use are the appetites? 

Name some false appetites. 

What is intemperance ? 

Why is fermented wine harmful, while the fruit juice of which it 
is made is a good food ? 

How is vinegar made ? 

Name some uses of alcohol. 

What is wood alcohol ? 

Why is it right to have laws regulating the sale of strong drink ? 
What is the Eighteenth Amendment to the Constitution of the 
United States? 

What is a stimulant ? a narcotic ? 

What is nicotine ? What are its effects on the body ? 

What effect does tobacco have on young persons? 

Why are cigarettes often more harmful than large cigars? 

What is opium? morphine? 

What is the danger from the use of opium in treating a pain ? 
What harmful effects do headache cures often have? 


For the Teacher. — There is great need to teach the nature and effects of 
stimulants and narcotics. The deceitful sense of strength and well-being 
which they produce is to be contrasted with the real strength which is pro¬ 
duced by proper food and rest. Three great facts about stimulants and nar¬ 
cotics are almost universally admitted: 

1. The very great harm which they do. 

2. The desirability of limiting their use. 

3. The right of the government to control or prohibit their sale. 

The following points are to be emphasized: 

1. Appetites, their value and their abuse. False appetites, and the dangers 
to which they lead. 

2. Alcoholic stimulants, their nature and the false sense of power which 
they excite. 

3. What drinks are alcoholic stimulants? 

4. The Eighteenth Amendment, and the laws for its enforcement. 

5. The duty of citizens to enforce the prohibition laws. Personal inde¬ 
pendence. Rights and privileges of individuals are to be laid aside for the 
benefit of the rest of the people. 

6. The danger of tobacco to young and growing persons. 


CHAPTER VII 


BONES AND JOINTS 



The Skeleton. — The flesh is supported by a bony 

framework called the skeleton. 
skuii The bones weigh about one sev¬ 
enth as much as the whole body. 
They give firmness, stiffness, and 
shape to the body. The size 
of the skeleton fixes the size 
of the body. If the bones are 
long and large, the body will 
be tall and large, but if they 
are small and short, the body 
will be small in size. 

' • j l, 

A bone is shaped somewhat 
like the part of the body in 
which it lies. Most of the 
bones of the arms, legs, hands, 
and feet are long and straight, 
like rods, and most of the bones 
of the head are flat and thin, 
like sheets of cardboard. The 
picture of a skeleton looks 
something like the picture of a 
very thin man, for the shape of 
every part of the body is out- 
A Human Skeleton lined in bone. 


Jawbone 

Spine 

Collar bone 

Shoulder 

blade 

Ribs 

Humerus 

Radius 

Ulna 

Pelvis 


Femur 


Tibia 

Fibula 


68 











BONES AND JOINTS • 69 

Names of Bones. — There are about two hundred 
separate bones in the body, and each one has a name. 
The long bone which reaches from the shoulder to the 
elbow is called the hu'merus. Two long bones extend 
from the elbow to the wrist, namely, the ra'dius on 
the thumb side of the arm, and the ul’na on the little 


Elbow of a Three-Year-Old Child Elbow of a Grown Man 

(X-ray photographs.) In the child’s elbow the ends of the bones are still soft, and 
contain so little lime that they do not show in the picture. In the man’s elbow all 

parts of the bone are hard and full of lime. 

Joints. — Bones are joined together in such a way 
that most of them may turn at the joints. The elbow 
joint is formed by the rounded end of the humerus 
fitting into a rounded notch in the ulna. The arm can 
bend at the elbow back and forth in only one direction, 
for the socket of the bones is long, and is rounded in 
only one direction, like a door hinge. The joint at 
the shoulder is shaped like half a ball, and allows the 
arm to turn in every direction. 

The backbone is made up of twenty-six bones which 
are piled one upon another like a long string of spools. 



finger side. 












70 BONES AND JOINTS 


Ligaments of the Shoulder Joint of a 

Sheep 

The joint is cut open to show the smooth, rounded 
upper end of the leg bone. 


They are joined together by tough pads of flesh in such 
a way that the whole string of bones may bend some¬ 
what, although the 
motion is slight 
between any two 
bones. 

The edges of the 
bones of the skull 
are very irregular, 
and are fitted to¬ 
gether like a dove¬ 
tailed joint in a 
box. These bones have only a very slight motion at 
their joints. The only bone 
of the head which can move 
freely is the lower jaw. 

Ligaments. — Bones are 
joined together at the joints 
by strong connective tissue 
bands called ligaments. 

What we call gristle on a 
soup bone is composed mostly 
of ligaments. Many of the 
tendons of muscles are also 
fastened to the bones at the 
joints, and act as ligaments 
to hold the bones in place. 

The ligaments of a shoulder, 
or elbow, or other joint which may be freely moved, 


Tendons Fastened to the .lig¬ 
aments of the Shoulder Joint 
of a Sheep 

The tendons help to hold the bones 
in place. 









BONES AND JOINTS 


7i 


surround the bones like a collar, thus forming a pocket 
within which the ends of the bones turn. Each pocket 
contains a liquid, called the syno'mal fluid , which 
makes the ends of the bones smooth and slippery, like 
an oiled hinge. 

The bones of the wrist are small and rounded, like 
pebbles. Ligaments of connective tissue bind them 
together so firmly that they seem like a single bone. 
Yet the ligaments will stretch slightly when the 
wrist is struck or strained, and the wrist will not be 
broken so easily as it would if composed of a single 
bone. 

Sprained Joints. — When a joint is turned too far, 
or in the wrong direction, the ligaments are stretched 
and torn. The joint then becomes sore and swollen, 
and the skin around it may become blue from the bleed¬ 
ing of the torn ligaments. 

We may help a person who has a sprained joint by 
soaking the joint in hot water for an hour or two. 
Then a bandage wound snugly around the joint will 
help to prevent the pain and swelling from returning. 
After a rest of two or three days a sprained joint will 
be helped by moving it, even if the motion causes 
some pain. If the joint is not moved early, the torn 
ligaments may grow together too short, or may grow 
fast to the bone, and the joint will then be stiff and pain¬ 
ful for a long time. 

Dislocated Bones. — When the ends of the bones in 
a joint slip past each other, we say that the bones are 


7 2 


BONES AND JOINTS 


out of joint, or dis'located. Putting a bone out of joint 
tears some of the ligaments of the joint. 

Boys sometimes put their fingers out of joint in 
playing baseball. If a finger is out of joint, you can 
put it back in place by pulling upon it. 

If a large joint, such as an elbow, is dislocated, bind 
the limb to the body, or to a narrow board, so as to 
keep the injured parts at rest. You can then move 
the person home without danger. A physician should 
be called to put the limb in place. 

Structure of Bones. — The shafts of long bones, 

such as those in 
the arms and legs, 
are hollow, like the 
frame of a bicycle. 
Their ends are like 
a fine honeycomb, 
or a sponge, cov¬ 
ered with a shell of 
hard bone. This arrangement makes them light and 
yet strong. A long bone is about twice as strong as 
an oak stick of the same size. 

A flat bone, like one from the head, is composed of 
two sheets of hard bone, separated by a network of 
spongy bone. By this means the parts inside of the 
head are protected much better than if the bone were 
a single sheet. 

A dried bone is two thirds lime and nearly one third 
connective tissue. Soaking a bone in a mixture of one 



A Long Bone Sawed in Two Lengthwise 
Its middle part is hollow, and its ends are spongy. 




BONES AND JOINTS 


73 


part of hydrochloric acid in ten parts of water will 
remove the lime, leaving the bone so soft that it may 
be tied in a knot. Burning a bone will remove the con¬ 
nective tissue and leave the lime. 

Bone Cells. — The living part of bone is composed 
of cells of connective tissue, arranged in circles around 
the blood tubes. 

The cells have 
small bodies, and 
a great number of 
fine branches. 

Their special work 
is to take lime from 
the blood, and to 
fix it among their 
branches in order 
to make the bone 
hard and stiff. 

Every cell of the 
body takes a small 
quantity of lime 
from the blood for 
its own use, but bone cells take a great deal of lime, 
and use it for the benefit of the whole body. 

Cartilage. — A thin, tough pad of gristle, called 
car'tilage , covers the end of each bone in a movable 
joint. A layer of cartilage also joins the bones to¬ 
gether in immovable joints. Cartilage is like bone 
which contains only a little lime. Each bone of a 



Bone Cells 

(Magnified 200 times.) The circle in the center is a 
blood tube. The cells are the living parts of bone 
and are arranged in circles around the blood tubes. 





74 


BONES AND JOINTS 


very young child consists largely of cartilage which 
takes up lime and becomes true bone as the child grows. 




■ H WBZ 




: n 


v\Vv; . : 

ikitf i M 0 






K 



Hand of an Eight-Year-Old 




Hand of a Thirteen-Year-Old 
Child 

The ends of the long bones are separated from the shafts by 
soft cartilage which gradually hardens as the child grows older. 


The wrist bones are only half 
formed. 

(X-ray photographs.) 


Bone Deformities. — While the bones are young 
and soft, they may bend slightly if pressure is put upon 
them. If the pressure is kept up day after day, the 
bones may grow crooked and deformed. The weight 
of the body may bend the bones of a poorly nourished 
baby, thus producing bowlegs. The backbone of a 
child may grow crooked from his sitting at a desk which 
does not fit his back. If a child has his nose so stopped 
up that he has to breathe through his mouth, the bones 
of the upper jaw may be compressed sidewise so much 





BONES AND JOINTS 


75 


that the upper teeth project beyond the lips. One may 
prevent most deformities of a child’s body by paying 
attention to the bones while the child is growing. 

Children that are fed with only bread and coffee, 
or other deficient food, may not take enough lime into 
their bodies to make their bones hard. These children 
often suffer with a disease called rickets , in which the 
bones are soft and easily deformed. Rickets may be 
prevented or cured by giving the children a variety of 
nourishing food, including fresh vegetables and milk, 
in order to supply all the substances which are 
needed to form good bone. Children who do not get 
fresh vegetables, fruit, and milk often have a disease 
called scurvy , in which the gums, teeth, and bones be¬ 
come sore and tender. Children who have what were 
formerly called “ growing pains ” usually have a mild 
form of scurvy which may be prevented or cured by 
proper food. 

Bone Diseases. — The solid part of a bone contains 
blood tubes, and grows in the same way that flesh 
grows. Disease germs may enter a bone, and cause 
it to become swollen and softened. Hip-joint disease 
is a form of lameness caused by the germs of tuber¬ 
culosis growing in and around the hip joint. Hunch¬ 
back is caused by tuberculosis germs growing in some 
of the bones of the upper part of the backbone, and 
causing them to become so soft that the weight of the 
body flattens them. 

Repair of Injured Bones. — A bone is covered with 


76 


BONES AND JOINTS 


a tough skin, called periosteum (per-i-os'tg-um), which 
helps to form new bone when the old bone is injured 
or diseased. When a bone is broken, the connective 
tissue cells form new cells, and fill the space between 
the two ends with soft flesh. The new flesh then takes 
up lime, and in a month or two it becomes stiff bone. 

How Bones Become Broken. — The usual way in 

which a person breaks a 
bone is by falling upon it 
in such a way that .his 
weight comes upon it like 
a sudden blow. A child’s 
body does not fall with so 
much force as the body of a 
heavy man, and so a child’s 
bones may not be broken 
by a fall which would break 
the bones of a man. 

The bones of a child do 
not contain so much lime as 
the bones of a grown person, 
and they may safely bend 
more than the bones of a man. 

Too much lime in a bone makes it weak and brittle, 
like the stem of a clay pipe. Bones take up more and 
more lime as a person grows older, and old persons often 
get broken bones from falls which are too slight to 
harm a young man. 

What to Do for a Broken Bone. — A broken bone is 



X-Ray Photograph of a 
Broken Bone 

The break is in one of the bones 
in the arm near the wrist. 






BONES AND JOINTS 


77 



painful, and the flesh near the break is usually bluish 
because of the bleeding of the bone. A break may be 
only a crack in a bone, and may appear like a bad 
sprain. It is often impossible to tell a break from 
a sprain unless an X-ray photograph of the bone is 
taken. It is im¬ 
portant to know 
whether or not a 
bone is broken, 
for rubbing and 
moving the in¬ 
jured part will 
harm a broken 
bone, but may help 
a sprain. 

If a bone is 
broken in two, it may be bent at the broken spot. 
A slight motion will cause great pain by rubbing the 
broken ends together. 

You can help a person who has a broken bone by 
binding a stick or a thin board along the whole length 
of the limb, using handkerchiefs for bandages. After 
you have done this, the bones cannot move, and you 
can carry the injured person home without danger to 
the broken part. 


A Broken Arm with a First-Aid Splint 

A thin board or strip of pasteboard, bound along the 
broken bone, makes a good first-aid dressing. 


QUESTIONS 

What is the skeleton? 

What is a joint? 

Describe a joint like the elbow. 








78 


BONES AND JOINTS 


Describe a joint like those between the bones of the backbone. 

Describe a joint like those between the skull bones. 

What is a ligament? 

What happens to ligaments when a joint is sprained? 

What should you do for a sprained joint? 

What should you do for a bone that is out of joint? 

How can you show that a bone is composed of both flesh and 
mineral matter? 

What is cartilage? 

What is a common cause of deformed bones? 

What is a common cause of bone diseases? 

How is a broken bone repaired ? 

Why do the bones of a child not become broken so easily as those 
of a grown man? 

What should you do for a person who has a broken bone? 

For the Teacher. — The older lessons in physiology usually began with the 
subject of bones as the framework of the body, and emphasized their number, 
names, forms, and uses, but made little reference to health. Some interest was 
given to the study by adding a little comparative anatomy and tracing ho¬ 
mologies, such as those between arms, wings, and fins. 

Later lessons emphasized the bones from the standpoints of posture and the 
graceful carriage of the body; but these subjects are in the special fields of 
the physical training teacher. 

The teacher of hygiene is especially interested in bones as living tissues. 
Bones are full of blood tubes and nerves, and may be considered as flesh which 
is hardened with lime. They are subject to accidents, diseases, and inflamma¬ 
tions, just as soft flesh is. They are also subject to two nutritional diseases, 
rickets and scurvy. These are the topics which need to be emphasized by a 
teacher of hygiene. Defects of joints are closely connected with those of mus¬ 
cles, and are considered in the next chapter. 


CHAPTER VIII 


MUSCLES 

Involuntary Muscles. — Nearly all movements in 
the body are produced by groups of cells called muscles. 
The movements are of two kinds. One kind is that 
which the mind cannot control, such as the flow of 
blood through the body, and the passage of food through 
the organs of digestion. The muscles which produce 
these movements are called involuntary muscles. 

Involuntary muscles are almost white, or colorless. 
Most of them are in the form of thin sheets surrounding 
the blood tubes and the tubes in which food is digested. 
They are composed of cells which are thick in the middle 
and taper toward their ends. When the cells act, they 
make themselves thicker and shorter. In this way 
they lessen the size of the tube which they surround, 
and produce motion in anything which the tube may 
contain. 

Voluntary Muscles. — A second kind of motion in 
the body is that which is under the control of the mind, 
such as the movements of the arms, legs, and head. 
The cells which produce these movements are called 
voluntary muscles. By the word muscle we usually 
mean a voluntary muscle. 


79 


8o 


MUSCLES 



The muscles of the body of an animal are its lean 
meat. The muscles of a person are like the lean meat 
of a lower animal, and form about half of the weight of 

the body. Most of them 
surround the bones, and lie 
just beneath the skin. 

There are about four hun¬ 
dred separate muscles in the 
body, each of which has a 
name. The muscle which 
lies on the front side of the 
arm above the elbow is 
called the biceps (bl'seps) 
muscle. Its use is to bend 
the elbow. The muscle which 
lies on the back side of the 
upper arm straightens the 
elbow, and is called the 
hi'ceps muscle. 

Examination of a Muscle. 

Muscles and Tendons on ^ T , 

the Front Side of a Cat’s ^ ou can see what your own 

Leg muscles are like by looking 

The white cords are tendons 

which straighten the toes. at the meat in a butcher’s 

shop, for the muscles of the common lower animals 
are nearly the same in number and arrangement as 
the muscles of your own body. A leg of lamb con¬ 
sists of bundles of muscles surrounding the leg bones. 
Each muscle is large at its middle or upper end, and ta¬ 
pers toward its lower end, where it ends in a strong 




MUSCLES 


81 

white cord of connective tissue called a tendon. The ten¬ 
don is fastened to a bone in the lower part of the leg. 

How a Muscle Acts. — When a muscle acts, it makes 
itself hard and firm, and becomes larger around and 
shorter than when it is 
at rest. In this way 
it draws its ends toward 
its middle part, and 
causes its tendon to 
pull upon whatever is 
fastened to it. The 
shortening and harden¬ 
ing of a muscle is called 
its contraction. 

Nearly all the mus¬ 
cles of the arms and legs are arranged like the muscles 
in the leg of a lamb. The upper end of each muscle is 
fastened to a bone, either in the trunk or in the upper 
part of a limb. The tendon at its lower end is fast¬ 
ened to another bone after crossing the joint. Each 
muscle usually connects two bones, and its action 
is to make the lower bone move at the joint like a 
door on its hinges. Nearly all voluntary motions of 
the body are the bending of joints. 

You can see how a muscle acts by examining your 
own arm. Bend your elbow as far and as strongly as 
you can, and feel the biceps muscle swell in a hard 
bunch. Feel in the bent side of the elbow for the ten¬ 
don as it pulls upon the forearm. 

OV. GEN. HYG. — 6 



Tendon 


Muscles and Tendons on the Back 
Side of a Cat’s Leg 


The tendons bend the toes and the claws. 






82 


MUSCLES 


Face Muscles. — Many of the muscles of the face 
are fastened to the skin. When they contract, they 
move the lips and cheeks, wink the eyelids, and wrinkle 
the skin. The motions of the face often show how a 
person feels. If he is happy, his muscles will pull the 
corners of his mouth upward and backward in a smile. 
If he feels sad or is in pain, other muscles will pull the 
corners of his mouth downward, as in crying. If he is 
angry, the muscles will wrinkle his forehead in a scowl. 

The face muscles which you use often will produce 
marks and wrinkles on the skin, and will show a great 
deal about your character and disposition. If you 
smile often, you will carry the marks of the smile 
through life. If you are often angry, you will carry a 

scowl upon your forehead. If 
you practice kindness and gen¬ 
tleness while you are young, 
you will carry their signs on 
your face all through life. 

Structure of Muscle. — A 
voluntary muscle is composed 
of cells about the size and 
shape of short fibers of cotton. 
Muscle Cells If you \ 0Q ^ a f muscle cells 

(Magnified 300 times.) Muscle cells i mirrrmrnnp von ran 

are like ribbons or strings; they Under a miCrOSCOpe, yOU Cdn 

have lines running across them. gee f a j n t fines running acrOSS 

them. The cells lie side by side, and are held in their 
places by fine branches of connective tissue cells. 
Muscle cells are soft like jelly, but the connective tissue 








MUSCLES 


83 



cells around them are almost as tough as fibers of cot¬ 
ton. The toughness of meat is due to the connective 
tissue in it. 

The special work of muscle cells is to shorten them¬ 
selves in order to produce motion in some other part 
of the body. There is a slight motion among the par¬ 
ticles of every living cell, 
but a muscle cell can move 
so much that it produces 
motions in other parts of 
the body. 

A tendon is composed 
of connective tissue fibers 
which are fastened to the 
connective tissue of the 
muscle. 

Strength of Muscle. —A 

muscle one inch in diameter 
can lift about seventy-five pounds. Frogs and grass¬ 
hoppers seem to be much stronger for their size than 
a man, but this is only because their bodies are lighter. 
A piece of their muscle is only half as strong as a bit 
of man’s muscle of the same size. 

Source of Muscular Strength. — A fine network of 
blood tubes surrounds each muscle cell. The blood 
which flows through the tubes brings both food and 
oxygen to the cells. When a muscle contracts, it takes 
some of the oxygen and oxidizes either some of the 
food, or some of its own substance (p. 33). The ox- 


Muscle Cells (a) Cut Across 

(Magnified ioo times.) The substance 
( b ) between the groups of cells is con¬ 
nective tissue. 










8 4 


MUSCLES 


idation supplies the power and strength which the 
muscle puts forth in its work. 

The contraction of a muscle may take place in an 
instant, like the uncoiling of a spring suddenly re¬ 
leased, or the muscle may contract slowly, like a spring 
pulling steadily. A contraction is started by an order 
which the brain sends to the muscles by means of a 
nerve. 

Muscle Growth. — Using the muscles is called ex¬ 
ercise. A muscle at rest takes very little food and 
oxygen from the blood. If muscles are not used, they 
soon become small and weak, but when they work, 
they use up a great deal of food and oxygen, and take 
in a large supply from the blood. Muscle cells are 
living things, and when they are often called upon to 
do work, they prepare themselves for it by storing 
up a supply of food in their own substance. For this 
reason exercise makes the muscles grow large and 
strong. 

Many young persons take exercise to make their bodies 
grow healthy, shapely, and beautiful. They go to gym¬ 
nasiums to have the size of the muscles measured, and 
their strength tested, and to have the instructors tell 
them what exercises will increase their size and strength. 
If their upper arms are small, they take exercises which 
require the arms to be moved at the elbow, and in this 
way they increase the size of their biceps and triceps 
muscles. A young person can develop the muscles of 
any part of the body by exercising them. 


MUSCLES 


85 


Foot Exercises. — Weak ankles and flat feet are 
often painful in persons who stand or walk for hours. 
They are the result of a weakness of the muscles whose 
cords extend down beside the ankles and hold the foot 
firmly in position. 

A flat foot is one 
whose arch is 
turned downward. 

If a person walks 
with the toes 
pointing outward, 
the arch of the 
foot is turned 
downward at each 
step as the body 
swings forward on 
the foot, but if 
the toes are turned 
inward, the arch 
is lifted up at 
each step. 

Flat feet may be prevented, or cured, by walking with 
the toes pointed inward as far as possible for five min¬ 
utes each day. This exercise will strengthen the mus¬ 
cles which lie on the front of the leg below the knee, 
and which hold the arch of the foot upright. 

Crippled Children. — Muscles which are not used 
become soft, weak, and small. One of the principal 
causes of the crippling of children is muscular weakness 



An Exercise to Prevent Flat Feet 

Walking “pigeon-toed” strengthens the muscles 
which hold the arch of the foot upright and 
make the ankles firm. 








86 


MUSCLES 


or disease, especially infantile paralysis , or poliomyelitis 
(pol-i-o-ml-e-ll'tis). This disease begins in the spinal 
cord and prevents a person from sending nerve mes¬ 
sages to the muscles directing them to produce move¬ 
ments. The muscles then become weak and small, 
because the brain cannot send the orders to move them. 

Muscles are arranged in opposing groups. For ex¬ 
ample, a group on the back side of the thigh bends the 
knee, and another on the front straightens it. If the 
muscles which straighten the knee are weak, the strong 
ones on the back of the thigh shorten themselves and 
hold the knee bent, because those on the front of the 
thigh cannot pull against them. Joints which are stiff 
or deformed are often made so by contractures of the 
muscles when the bones and joints themselves are all 
right. These deformities may be prevented by proper 
movements or exercises which prevent the stronger 
muscles from contracting too much. When the de¬ 
formities are fully developed, they may be overcome 
by a simple operation. 

Round Shoulders. — The principal support of the 
arms and shoulders are the muscles on the back side 
of the neck and trunk. If the muscles are weak, the 
shoulders fall forward, producing round or stooped 
shoulders. The straight back and full chest of a sol¬ 
dier are due to training the muscles which hold the 
shoulders up. You can exercise the muscles of your 
back by always holding your shoulders up when you 
sit or stand. In a little while your muscles will grow 



MUSCLES 87 

so strong that they will support your shoulders with¬ 
out your thinking about their action. 

Good posture and a graceful carriage of the body 
are produced by strong muscles. By practicing the 
proper posture both in sitting and in walking, you can 
train your muscles to hold your body in postures 
which are healthful and graceful. 

Exercise and Endurance. — Exercise trains the mus¬ 
cles to work for hours at a time, and to endure hard 
labor without tiring. Athletes and circus actors have 
to take exercise every day in order that their muscles 
may endure their work. If they should stop exercising 
for a few days, their muscles would become tired soon 
after they begin to do their acts. 

Every person has to make some use of his muscles. 
Even writing at a desk requires muscular work to hold 
the body upright, and is extremely tiresome to those 
whose muscles are weak. Many boys and girls at school 
fail in their work because they do not cultivate enough 
muscular strength to enable them to sit at their desks 
all day. Riding in an automobile or in a railroad train 
requires an amount of muscular work which often tires 
a strong man. You cannot have strength and endur¬ 
ance to carry on your daily work unless you take ex¬ 
ercise every day. 

Exercise and Health. — One of the greatest of all 
reasons for taking exercise is to keep the whole body in 
good order. Muscles use up the greater part of the 
food and oxygen which enter the body. When you 



88 


MUSCLES 


do not use your muscles, you have very little need of 
food. You do not have much appetite, and your 
stomach digests only a little food. You also have very 
little use for oxygen, and you breathe lightly. All 
the actions in your body are lessened, and you feel 
dull and weak all over. You must take exercise if 
you would keep your body well and strong. 

The steps by which exercise benefits your body are 
as follows: 

i i. Your muscles use much oxygen in the process of 
oxidation. 

2. You breathe deeply and often, and become long- 
winded. 

3. Your heart pumps blood rapidly in order to sup¬ 
ply the muscles with an increased amount of food and 
oxygen, and to remove their waste matter. 

4. You feel pleasantly tired and can rest and sleep 
well. 

5. You have a good appetite and can digest your food 
well. 

6. Your muscles gain strength and endurance. 

7. Every part of your body is strengthened by the 
exercise of your muscles. 

Fatigue. — When excessive exercise is taken, great 
amounts of waste products are formed and are poison¬ 
ous to the whole body. Fatigue is due as much to a 
poisoning by waste matters as it is to an exhaustion of 
the available food of the muscles. While a slight degree 
of fatigue is natural a.nd leads to rest and sleep, yet a 


MUSCLES 89 

greater degree of fatigue is harmful, especially to young 
persons. 

Rest and Relaxation. — If muscles are to be healthy 
and strong, they must spend more time in rest than in 
contracting. When muscles are at rest, they are soft 
and relaxed, the joints are loose, and the limbs hang 
limp. You cannot rest well unless your muscles are 
completely relaxed while you sit or lie down. Some 
persons have difficulty in relaxing their muscles. Prac¬ 
tice sitting in a chair in such a way that your whole 
body is relaxed and your arms, legs, and head hang 
limp like a piece of cloth. 

Kind of Exercise. — While you sit at a desk all day, 
you use your muscles in a gentle way which finally 
tires them, but the work which they do does not require 
you to breathe deeply, or your heart to beat hard. 
The kind of exercise which helps you most is that 
which makes you breathe deeply, sends the blood to 
your face, and warms your whole body. Every man, 
woman, and child needs at least an hour of this kind 
of exercise every day. Children at school cannot have 
clear minds unless they take this exercise. 

If you have to work with your hands, you will get 
exercise while you work. Farmers, carpenters, errand 
boys, and housemaids all get exercise while they do 
their work. But students and bookkeepers often have 
very little muscular work to do, and they may get 
exercise by walking, bicycling, rowing, fishing, playing 
outdoor games, and taking part in athletic sports. 



90 


MUSCLES 


One of the best ways of taking exercise is to become 
interested in some kind of active work or sport. Fads 
and sports, such as photography, gardening, and fish¬ 
ing, have often been the means of leading sickly per¬ 
sons to take needed exercise, restoring them to health. 

Muscles need pure, fresh air as much as they need 
good food. The best exercise is that which is taken out 
of doors where the air is pure and free from dust. 

Mental Effects of Games. — Playing athletic games 
develops those qualities which are useful in after life 
in earning a living, and in performing the duties of 
citizenship. Among the . excellent qualities which 
games develop are the following : 

Respect for rules and laws. 

Obedience to leadership. 

Fair play, honesty, loyalty, and chivalry. 

Respect for the rights of others. 

Team work and cooperation. 

A sense of responsibility. 

Endurance, fortitude, persistence, and self-control. 

Attention and alertness. 

Skill and grace in movements of the body. 

Gymnasiums and Playgrounds. — Children in large 
cities often have no work to do, and nowhere to play. 
It is the duty of those who have them in charge to pro¬ 
vide the means and the places for their exercise. It is 
a good investment for taxpayers to give their money for 
gymnasiums, playgrounds, and parks, where children 
can play and develop strong, healthy bodies. 




MUSCLES 


9i 


Alcohol and Muscular Strength. — Many experi¬ 
ments have been made to find out whether or not 
the use of an alcoholic drink will increase a person’s 
strength. These experiments have always proved that 
alcohol lessens the strength instead of increasing it. 
Athletes in training are not allowed to drink any form 
of alcoholic liquor at all. 

Alcohol and Endurance. — Experiments have been 
made to find out whether or not alcohol will help a per¬ 
son to put his muscles to hard use for hours at a time. 
They prove that alcohol lessens the endurance. No 
civilized nation now supplies alcoholic drinks to its 
soldiers and sailors as was formerly done, for on long 
marches and in severe hardships those who drink 
are the first to fail in strength: No explorer in deserts 
and arctic lands will allow his men to use strong drink. 

1 

Alcohol and Accuracy of Motion. — Experiments 
have been made to find out whether or not alcoholic 
drinks will help a person to do quick and accurate work 
with his muscles, such as setting type or shooting at a 
mark. It is proved that alcohol always lessens the 
speed and accuracy of the worker. But very often it 
deceives a person and makes him believe that he is doing 
his work more quickly and accurately. 

Tobacco and Muscles. — The nicotine of tobacco is 
a poison to the muscles. Tobacco cannot increase the 
strength. Soldiers, sailors, and explorers sometimes 
say that tobacco helps them to do their work. They do 
not use tobacco to increase their strength, but to help 


92 


MUSCLES 


themselves to be contented and to rest after doing hard 
work. If tobacco were of any value in helping tired 
persons to rest, it would be used in sickness. But those 
who smoke or chew do not care to do so when they are 
sick, for they then feel the poisonous effects of the nic¬ 
otine just as if they had never used tobacco. 

Tobacco is more poisonous to the muscles of a young 
man than to those of a grown person. A boy who 
smokes cigarettes cannot become a good athlete, nor 
endure hard work. The use of cigarettes will spoil a 
boy’s reputation as a worker, and those who wish to 
employ bright, active boys will not take cigarette smok¬ 
ers if they can help it. 

QUESTIONS 

What is the difference between an involuntary muscle and a 
voluntary one? 

Where may involuntary muscles be found? 

How much of the body is composed of voluntary muscles? 

How many muscles are in the body? 

Where is the biceps muscle? the triceps? 

What is a tendon? 

What change takes place in the shape of a muscle when it starts to 
act? 

To what are the muscles of the arms and legs fastened? 

When a muscle acts, what does it do to a bone or joint ? 

How do the muscles of the face produce a smile? 

What is the shape of a muscle cell? 

What is the use of connective tissue between the cells? 

How many pounds can be lifted by a muscle one inch in diameter? 

From what does a muscle get its power to act? 

What makes you feel warm when you work hard with your muscles? 


MUSCLES 


93 


What causes muscles to act? 

What is exercise? 

What are some of the benefits which you may get from taking 
exercise ? 

If your arms are small, how may you increase their size? 

If you become tired out after walking a few blocks, how can you 
increase the endurance of your muscles? 

What are the causes of fatigue? 

What are some of the mental effects of playing games? 

What is infantile paralysis or poliomyelitis? 

How may diseased muscles cause stiffness and deformity of joints? 

What is the cause of weak ankles and flat feet ? How may these 
defects be prevented or cured? 

How does exercising your muscles help your lungs ? 

Name some good kinds of exercise. 

Give a reason why the people of a city should vote money to pay 
for gymnasiums and playgrounds. 

What effect does alcohol have upon muscular strength? upon 
endurance? upon accuracy of movements? 

What effect does tobacco have upon the muscles? 


For the Teacher. — The subject of muscular exercise is of very great im¬ 
portance in keeping the body healthy and vigorous, and more attention is 
often given to it than to any other topic in hygiene. The physical training 
teacher is first of all a muscle trainer. About half of all health articles in 
magazines are devoted to the subject of exercise. A teacher of hygiene 
needs to teach only the general principles of the hygiene of muscles in the 
classroom. 

One topic to be emphasized is the relation between muscles and crippled 
joints. While joints may be crippled by tuberculosis or other diseases, yet 
the most common form of crippling is that caused by infantile paralysis or 
poliomyelitis, which is primarily a disease of the spinal cord and secondarily 
of the muscles. Muscular unbalance and contractions of the stronger muscles 
are common causes of stiff joints and deformed feet. The great number of 
crippled children makes it desirable to teach this topic at some length. Em¬ 
phasize the fact that most crippled conditions of children may be prevented 
or cured if the directions of skilled physicians are followed patiently for months. 

Another important topic is that of weak ankles and flat feet. About 
twenty per cent of all children have these physical defects, and yet these may 
be easily remedied by proper exercises, especially by walking “pigeon-toed.” 


CHAPTER IX 


i 


CIRCULATION OF BLOOD 

Use of Blood. — The cells of the body eat, breathe, 
and grow like separate microscopic animals outside of 
the body. They cannot go in search of food and 
oxygen, but everything which they need is brought to 
them by a red liquid that is always flowing through 
every part of the body. This liquid is the blood. The 
blood also takes away the waste matters which the cells 
give off, and it protects the cells from disease germs 
which may enter the flesh. The life of the body de¬ 
pends upon the blood. 

Composition of Blood. — Blood consists of a clear, 
yellow liquid called plasma (plaz'ma), or se'rum , which 
is full of cells called blood cells, or cor'puscles. About 
one half of the blood is plasma, and the other half is 
blood cells which float in the plasma. 

Plasma. — The plasma of the blood consists of water 
containing protein, fat, sugar, and minerals, all of which 
are to become food for the cells of the body. It also 
contains small quantities of waste matters which it has 
washed away from the cells. 


94 


CIRCULATION OF BLOOD 


95 


Clot. — After blood flows from the body, it becomes 
solid, like jelly. Blood in a solid form is called a clot. 
The effect of clotting is to form a solid mass which will 
stop the bleeding in a cut or wound. 

Red Blood Cells. — Most of the cells which float, in 
the blood are red, and give the red color to the blood. 



Red Blood Cells 

< 

(Magnified 500 times.) Under a microscope, these cells are usually seen as at the 
right, piled one upon another like coins. At the left they are shown partly sep¬ 
arated. They are light orange in color, but when millions of them are together, 

they appear red. 

One may easily see them by examining a thin smear of 
blood with a microscope. A red blood cell is shaped 
like a thick round plate with a hollow on each side. 

The use of the red blood cells is to carry oxygen from 
the lungs through the body. They do this by means of 
their red coloring matter, called hcemoglo'bin , which con¬ 
tains iron. 

White Blood Cells. — Some of the blood cells are 
round like balls, and are almost colorless, but when many 






g6 


CIRCULATION OF BLOOD 


of them are seen together they appear white. These 
are called white blood cells , or white corpuscles. One of 

their uses is to destroy bac¬ 
teria and other disease germs 
which have entered the body. 
We can see white blood cells 
by looking at the white matter 
from a pimple with a micro¬ 
scope. This matter consists 
of white blood cells killed 
by bacteria in the pimple. 

Arteries. — The blood in the body is held in tubes, 
and is kept in motion by a pump called the heart. The 
heart sends blood to every 
part of the body by means 
of a set of tubes called 
ar'teries. All the arteries, 
except those leading into 
the lungs, are branches of 
a single artery which begins 
at the heart and is called 
the aor'ta. The larger ar¬ 
teries lie deep in the flesh 
where they cannot be easily 
harmed. 

n-n i ... (Magnified 200 times.) The greater 

The larger arteries in part of the wall of the artery consists 

the body have been given of involuntary muscle, 

names. For example, the one on the thumb side of 
the front of the wrist is called the radial artery. 




White Blood Cells 

(Magnified 500 times.) The white 
matter from a pimple consists of 
white blood cells which have been 
killed while fighting disease germs. 





CIRCULATION OF BLOOD 


97 


Muscles of the Arteries. — The walls of the arteries 
consist largely of muscles which can contract or relax, 
and make the tubes small or large, according to the needs 
of the various parts of the body (p. 79). When a per¬ 
son is too warm from running, his face is red, because 
the arteries become large in order to allow a large 
amount of blood to flow near the surface of the body 
and become cooled. 

The contraction of arteries may be seen in an earth¬ 
worm. A large blood tube runs along its back and an¬ 
other along its under side. By watching a tube closely 
you can see it contract regularly about once every four 
seconds. The earthworm has no heart, but the regular 
contractions of the blood tubes keep the blood in motion. 

Veins. — The blood is returned to the heart by means 
of a set of tubes called veins. The veins are like the ar¬ 
teries, except that in them the blood flows from the 
small branches into the large trunks. These large 
trunks open into the heart. We can see veins on the 
back of the hand by holding the hand down at arm’s, 
length for a moment. The blood will fill the veins, and 
will make them look like bluish ridges under the skin. 
The larger veins in the body have been given names. 
For example, the principal vein on the side of the neck 
is called the ju f gular (joo'gu-lar) vein. 

Valves of the Veins. — Veins contain valves which 
open toward the heart. When a muscle contracts, it 
squeezes blood from its veins. The blood must flow 
onward, for the valves prevent it from flowing back- 


OV. GEN. HYG. — 7 



CIRCULATION OF BLOOD 


9 S 

ward. Thus exercise helps the flow of blood through 
the body. 

Proof of the Flow of Blood. — The movements of the 
blood were not known until an English physician, 
named William Harvey, discovered them and described 
them in a book printed in 1628. 



Vein full Vein empty between a valve and the 

thumb 


Experiment to Show the Action or Valves in the Veins 

Close the vein with the thumb over the knuckle. Squeeze out the blood by running 
a hnger up the vein. Lift the finger and blood flows backward only to a valve. Lift 

the thumb and blood fills the whole vein. 

You can easily perform one of his experiments to prove 
how the blood flows. 

Press a thumb upon a vein on the back of the hand, 
and rub a finger from it toward the heart in order 
to empty the vein of blood. Lift the finger and 
blood will return and fill the upper part of the vein down 







CIRCULATION OF BLOOD 


99 


to a set of valves, but the lower part of the vein will 
remain empty. Now lift the thumb, and blood at 
once fills the whole vein. This experiment shows the 
direction of the flow of blood in the veins of the hand. 

Capillaries. —- Blood goes from the smallest branches 
of the arteries into the smallest branches of the veins 
by passing 
through a set 
of fine tubes 
called capil¬ 
laries. The 
capillaries ex¬ 
tend around 
and between 
the cells of the 
body in a net¬ 
work so fine 
that every cell 
lies close to one 
or more of the 
tubes. Cap¬ 
illaries are so small that the separate ones cannot be 
seen without a microscope. They are so numerous and 
so close together that they make the skin look as if it 
were painted pink. Pressing a finger on the skin will 
force the blood from the capillaries, and when the finger 
is lifted it will leave a white spot for a moment until 
the blood fills the capillaries again. 

The walls of the capillaries are so thin that some of 



Capillaries around Muscle Cells 

(Magnified 200 times.) The larger black lines are the 
smaller arteries. 































IOO 


CIRCULATION OF BLOOD 


the plasma and oxygen from the blood easily soak 
through them and stay behind for the use of the cells, 
while the rest of the blood passes into the veins. At 
the same time, carbonic acid and other waste matters 
from the cells pass into the blood stream and flow 

away through the veins. 
Thus the capillaries distrib¬ 
ute food and oxygen to 
the cells and take away 
their waste matters. 

Seeing Capillaries. — 
You may see the flow of 
blood through the capil¬ 
laries by using a micro¬ 
scope and examining the 
tail of a very small fish, 
or the web of a frog’s foot. 
The blood cells in a capil¬ 
lary appear like orange- 
colored balls tumbling over 
and over as the blood car¬ 
ries them along. 

The Heart. — The heart is made of firm muscle, and 
is about the size and shape of a person’s fist. Its smaller 
end may be felt throbbing under the skin a little to the 
left of the lower end of the breastbone. It is hollow, and 
is divided into four compartments, two called au'ricles, 
and two, ven'tricles. Each auricle receives blood from 
the veins, and each ventricle sends it into an artery. 



Microscope Arranged to Show 
Capillaries in the Tail of a 
Small Fish 





CIRCULATION OF BLOOD 


IOI 


How the Heart Pumps Blood. — The ventricles have 
thick walls of muscle which form the greater part of the 
heart. Each ventricle has a door, or valve , opening in¬ 
ward from the auricle, and another valve opening out¬ 
ward at the beginning of the artery. A ventricle re- 



The Valve at the Begin¬ 
ning or the Aorta 


It consists of three cup-shaped 
parts (marked FFF) which 
close at the end of a heart beat. 



ceives blood from its 
auricle, and when it is 

full it suddenly con- Heart op A Theee . Months . 0ld lamb 

tracts and becomes (Natural size.) RA, right auricle; RV, right 
Smaller thus forcing ventr i c ^ e ! LA, left auricle; LV, left ventricle. 

the blood out. The valve at the auricle does not 
allow the blood to flow backward into the auricle, but 
the valve which opens outward allows it to flow into 
the artery. 

After the ventricle has emptied itself, its muscles relax 
and allow more blood to enter from the auricle, but the 
valve at the artery closes and does not allow the blood 





102 


CIRCULATION OF BLOOD 



to flow backward from the artery. In this manner 
the ventricles keep the blood flowing through the ar¬ 
teries away from 
the heart. 

Pulse. — The 
heart of a grown 
person contracts or 
beats about 7 5 tim es 
each minute, and 
each beat sends 
about four table¬ 
spoonfuls of blood 
into the arteries. 
The blood fl ows 
through the arteries 
in spurts or waves 
called the pulse beats. 
You can feel the 
pulse when you press 
lightly upon the flesh 
over a large artery. 
By feeling the pulse 
you can tell how fast and how strongly the heart is 
beating. One of the best places to feel the pulse is 
in the radial artery on the front of the wrist (p.'> 96). 

Circulation of Blood. —- The flow of blood through 
the body is called the circulation. 

A drop of blood will go the full rounds of the circula¬ 
tion in one or two minutes. In doing so (starting from 


Left Auricle and Ventricle Cut Open 

The valve between the auricle and the ventricle is 
marked VVV. It is thin and white like a piece of 
silk. Strong, white threads hold its edges firm 
when it is closed, as shown above. 





CIRCULATION OF BLOOD 


103 


the left ventricle) it will pass through the following 
structures: 

1. Left ventricle ✓ 

2. Arteries of the 

body 

3. Capillaries 

4. Veins from the 

body 

5. Right auricle 

6. Right ventricle 

7. Artery to the 

lungs 

8. Capillaries of 

the lungs 

9. Veins from the 

lungs 

10. Left auricle 

11. Left ventricle 

again 

Lymph. — The 

plasma that passes 
through the sides of 
the capillaries and 
goes to the cells is 
called lymph. It surrounds the cells of the body and 
fills all spaces among the tissues, like water in a sponge. 
The cells of the flesh lie in the lymph like fishes in 
water. They take their food and oxygen from the 
lymph and give off their waste matters to it. The 



Diagram of the Circulation 
The arrows indicate the direction of the flow of blood. 











104 


CIRCULATION OF BLOOD 


liquid which stands on the raw flesh after a bit of skin 
has been knocked from the knuckles is lymph. 

The Flow of Lymph. — The lymph in the flesh is 
slowly returned to the blood in the veins near the heart 
by a set of tubes called lymphat'ics. These tubes are 
so small and thin that they can scarcely be seen. They 
are arranged like the veins, and contain valves which 
allow the lymph to flow only toward the veins. When 
the muscles contract, they press upon the lymphatics 
and force the lymph out of the flesh and into the veins. 
Thus muscular exercise helps the flow of the liquid which 
nourishes and cleanses the cells. 

Rubbing the limbs toward the body is refreshing to 
a tired person, for it makes the lymph flow back to the 
veins, and thus removes the waste matters from the 
tissues. 

Circulation Compared with the Water Supply of a 
City. — The circulation of blood in the body is like the 
water supply of a city. 

The heart is like the pumping station. 

The arteries are like the pipes which lead from 
the pumping station, and send branches to the faucets 
in the houses. 

The flow of blood in the capillaries is like the flow 
of water from the faucets. The use of the arteries is 
to carry blood to the capillaries, just as the use of the 
water pipes is to carry water to the faucets. 

The veins are like the waste pipes and sewers which 
carry the waste water from the houses. A difference 


CIRCULATION OF BLOOD 105 

between them is that the veins return the blood to the 
heart to be pumped over again, while the sewers empty 
the waste water at a distance from the pumping station. 

Lymph is like water which has been drawn from a 
faucet, and is taken away to be used in cooking or wash¬ 
ing. After lymph has been used, it is returned to the 
veins, just as the water which has been taken away from 
the faucets is finally poured into the sewers. 

Bleeding. — The greatest danger to the circulation 
is that of bleeding from wounds. This subject will be 
discussed in the next chapter. 

Regulation of the Flow of Blood. — An organ at work 
must use far more blood than while it is at rest. If an 
organ cannot get a large amount of blood, it cannot 
work well; and if an increased amount of blood contin¬ 
ues to flow through it after its work is done, the organ 
cannot rest. A disturbance of the circulation produces 
bad effects almost at once. If, for example, too little 
blood goes to the brain, a person is faint; but too much 
blood in the brain produces headache and excitement. 

Disturbances of the circulation occur in three prin¬ 
cipal ways: 

1. In the heartbeats. 

2. In the pressure of the blood in the arteries. 

3. In the size of the arteries. 

Heart Disease. — A person whose heart is weak or 
diseased cannot run or do hard work with his muscles, 
for the muscles cannot get the amount of oxygen which 
they need. The most common sign of heart weakness 




ic6 


CIRCULATION OF BLOOD 


is a shortness of breath which is the result of the failure 
of the blood to carry a full amount of oxygen through 
the body. 

A person may think he has heart disease when he 
feels his heart beating hard, or his pulse throbbing in his 
head. These feelings are seldom caused by heart 
trouble, but they are due to overeating or other disturb¬ 
ance of the stomach, and they usually pass off when 
the stomach acts properly. 

The most common form of heart disease is leaking 
valves. When a valve leaks, the heart pumps hard in 
order to keep up the flow of blood. It often grows in 
size because of the increased exercise of its muscles. A 
damaged heart can repair itself better than almost any 
other organ in the body. A person with a leaking heart 
valve can usually live a healthy life, if he does not over¬ 
work his heart by hard exercise. 

Two common causes of heart disease are disease germs 
and too hard exercise. 

The Heart and Disease Germs.—When a person has 
diphtheria, or scarlet fever, or other infectious disease, 
the germs of the disease may poison the whole body, 1 
especially the heart. A great danger in any infectious 
disease is that the heart may remain weak after the 
sickness has passed off. 

The relation of diseased tonsils and teeth to heart 
disease will be described in Chapter XXV. 

The Heart and Exercise. — The heart regulates its 
beats according to the work which the body does. 



CIRCULATION OF BLOOD 


107 


When a person takes exercise, the heart beats strongly 
and rapidly in order to send a large amount of blood 
through the muscles. Exercise will strengthen the 
heart, as it will any other muscle in the body. But 
too hard exercise may overwork the heart and weaken 
it. Running long races until one can scarcely stand is 
an example of the kind of exercise which is harmful. 

The ability of the heart to endure exercise may be 
tested in the following way: 

1. Count the pulse after the person tested has been 
seated quietly for fifteen minutes. It will usually beat 
between 70 and 80 times a minute. 

2. Have the person run up and down a flight of stairs, 
or around the schoolhouse. 

3. Count the pulse a second time as soon as the 
person is seated. It will now beat over 100 times 
a minute. 

4. Count the pulse again every two minutes while the 
person remains seated quietly. If the heart is strong 
and healthy, the pulse count will drop to 70 or 80 within 
four minutes. 

This method of testing the heart should be used on 
every person who expects to take part in a hard athletic 
contest. 

Blood Pressure. — The heart forces blood through 
the arteries with enough pressure to cause a stream of 
blood to spurt up three or four feet when a large artery 
is cut. When a healthy person takes brisk exercise, the 
pressure of blood in the arteries increases, because the 



io8 


CIRCULATION OF BLOOD 



heart beats fast and hard; but the pressure soon falls 
when a person rests. A blood pressure which is either 
too high or too low has a great effect upon health and 
strength. Much ill health in grown persons is caused by 
Ghanges in their blood pressure. A physician tests 

the blood pressure by 
wrapping a flat rubber 
bag around the arm 
and pumping air into it, 
and noting the air pres¬ 
sure which closes the 
arteries and stops the 
pulse in the wrist. 

A high blood pressure 
is often associated with 
diseases of the kidneys 
and the arteries. 

Regulation of the 
Size of Arteries. — The 
circulation in a part is 
often disturbed by a 
failure of the arteries 
to regulate their size according to the amount of blood 
which the part needs (p. 97). The arteries of the 
stomach, for example, expand during digestion and con¬ 
tain an excess of blood, leaving too little blood to go 
to the brain ; and so one feels dull and sleepy after a 
heavy meal. Excitement causes the arteries of the 
brain to expand and to hold an excess of blood, and 


Taking the Blood Pressure 

The instrument shows the pressure which is 
needed to dose the main artery of the arm. 





CIRCULATION OF BLOOD 


109 

thus makes the brain too active and prevents sleep. 
Failure of the arteries to adapt their size to the needs 
of important parts of the body is a frequent cause of 
indefinite pains and other unpleasant feelings. 

Hardened Arteries. — A healthy artery is soft and 
elastic, like a new rubber tube, and can scarcely be felt 
when it is rolled under the fingers. It stretches with 
every beat of the heart, and contracts between the beats, 
and thus prevents the pressure from becoming either 
too great or too little for health. A common form of 
disease of the arteries is their hardening with lime. 
Hardened arteries are like tubes of old rubber, and can¬ 
not expand or contract to regulate the flow of blood to 
a part. A hardened artery is often weak and is in danger 
of bursting when the heart beats hard. Apoplexy is 
caused by the bursting of a hardened artery in the brain. 

Three common causes of hardened arteries are : 1, old 
age, 2, intemperance in eating or drinking, and 3, dis¬ 
ease germs, especially those growing in the tonsils and 
teeth. 

The walls of the arteries of old persons often become 
hardened with lime and may be felt like firm cords 
under the skin. Many of the effects of old age are the 
result of a hardening of the arteries. Infectious diseases 
and intemperance in eating and drinking may cause a 
hardening of the arteries of a young person, and cause 
that person to look and act like an old man. Leading 
a temperate life and avoiding infectious diseases are 
great helps in preserving the vigor of youth into old age. 



no 


CIRCULATION OF BLOOD 


QUESTIONS 

What is the circulation? 

Of what is blood composed ? 

What are red blood cells ? What is their use ? 

What are white blood cells? What is their use? 

What is plasma ? What is its use ? 

What effect does clotting have on bleeding? 

What are arteries? 

Of what use are the muscles in the walls of arteries? 

What are veins? Of what use are their valves? 

What are capillaries? 

What changes occur in the blood while it is passing through the 
capillaries? 

Describe the heart and its contractions. 

What is a ventricle? What is an auricle? 

What is the pulse? Where may the pulse be felt easily? 

Through what structures does a drop of blood pass in making a 
complete round of the circulation? 

What is lymph? 

What causes the lymph to flow in the flesh? 

What effect does exercise have on the heart? 

How may the ability of the heart to endure exercise be tested ? 

What is the most common sign of heart disease? 

What are some common causes of heart disease? 

How may the blood pressure be tested? 

What are some of the effects of hardened arteries? What are 
some of the causes of the hardening? 

For the Teacher. — This chapter on the circulation is divided into two 
parts: i, the general principles of the circulation, which are to be learned 
accurately ; and 2, the four practical applications of high blood pressure, 
heart disease, test for heart efficiency, and hardened arteries. 

The causes of circulatory diseases often date back to conditions which may 
be corrected in youth and childhood. Emphasize infected teeth and tonsils 
as causes of circulatory diseases. 


CHAPTER X 


EMERGENCIES 

Causes of Accidents. — Accidents are far more fre¬ 
quent in America than in Europe because of the ex¬ 
treme degree of the American feeling of personal freedom 
to do as one pleases. But American freedom requires 
every citizen to respect the rights and feelings of one’s 
neighbors and associates. It is the duty of every 
person not only to guard his own body against injury, 
but also to watch that he does not injure others. Safety 
first depends largely on good manners, courtesy, and 
a respect for the rights of others. 

There are three great causes of accidents: 

1. Ignorance, such as the running of automobiles 
and other machinery by unskilled persons. 

2. Carelessness, or a lack of a sense of responsibility. 

3. Recklessness, or taking chances when the danger 
is well known. 

One of the greatest influences in preventing accidents 
is an educated public sentiment which will not laugh 
at the ignorant, the careless, and the reckless ; but will 
condemn them as dangerous lawbreakers. 

Safety First. — Accidents are not necessary, and 
most of them could be prevented. Safety first is the 
great lesson which railroad officials, factory managers, 


112 


EMERGENCIES 


policemen, teachers, and other leaders are trying to im¬ 
press upon all the people. Among the principles which 
are taught in safety-first campaigns are the following: 

1. Care at railroad crossings and on cars. 

2. Attention at street crossings. 

3. Care in the use of firearms and fireworks. 

4. Care in throwing stones and other missiles, and in 
the use of sling shots. 

5. Care in handling knives, scissors, and other sharp 
instruments. 

6. Carefulness in driving automobiles. 

7. Refraining from tricks and practical jokes. 

8. Heeding safety signs. 

Fire Prevention. — One of the greatest dangers to 
property, health, and life is that from fire. It is far 
easier to prevent a fire from starting than to put one 
out. Among the points to which attention should be 
given are the following : 

1. Care in the use of matches and in extinguishing 
them before throwing them away. 

2. Care in disposing of lighted cigarettes and cigars. 

3. Care in starting bonfires and in watching them 
until they are entirely out. 

4. Care in the use of gasolene, benzine, turpentine, 
and other liquids which are explosive or inflammable. 

5. The danger of cleaning clothes with explosive 
liquids in a room. 

6. The danger of using rubber tubing instead of 
metal pipe in connection with gas fixtures. 



EMERGENCIES 


ii 3 

7. The danger of allowing rubbish to accumulate 
in back yards and near buildings. 

8. The necessity of knowing the location of the 
fire-alarm box and fire hydrant nearest your home and 
your school. 

9. The way to give an alarm of fire. 

10. The way to use a fire extinguisher. 

Panic. — Accidents nearly always happen suddenly, 
and the danger is usually over in a very short time. If 
an accident happens in a crowd, one of the greatest of 
the dangers is that people will hurt one another in try¬ 
ing to get away from the place. Often those who are 
in an accident do not take time to think, but they push 
and throw each other down, and in that way they often 
do more harm than the accident itself. When the per¬ 
sons in a crowd become filled with fear and act without 
thinking, like a flock of frightened sheep, we say that 
they are in a panic. A sudden danger which requires 
quick action is called an emergency. 

Fire Drill at School. — A cry of “ Fire ” in a 
crowded meeting place will often cause a panic. Lives 
have sometimes been lost in panics when a large 
number of people in a crowded hall have tried to 
escape at once from a harmless fire. Most panics 
are caused by too great a hurry to escape from a 
supposed danger. Two persons are all that can go 
through the usual-sized doorway at once. If half a 
dozen try to crowd through at one time, some one is 
likely to be hurt. 

OV. GEN. HYG. —8 



EMERGENCIES 


114 

Fire drills at school teach boys and girls how to go out 
of a building quickly and safely. When an alarm bell 
is rung, the pupils drop their books and march out of the 
building in good order. In this way a large schoolhouse 
can be emptied in less than two minutes. This is far 
less time than it would take a fire to spread in a danger¬ 
ous way. 

Boys and girls who have been trained in fire drills are 
likely to be cool and thoughtful when an accident 
happens or danger arises in any place. 

Learning to Swim. — A great many persons lose their 
lives because they do not know how to float in water. 
Many persons who can swim lose their lives in trying to 
save those who cannot swim, but who become fright¬ 
ened and pull their rescuers down with them. Nearly 
every daily paper in summer has news of drowning ac¬ 
cidents that have occurred during the day. Most of the 
drowned persons could have been saved if they had 
learned to be cool when in danger, and had helped those 
who tried to save them. All of them would have been 
saved if they had taken the trouble to learn to swim 
while they were young. 

It is your duty to learn to swim. Go to the water 
with a friend who knows how to swim, and make 
up your mind that you will not be frightened. Do as 
he tells you, and you will quickly learn to swim. 

If a person is nearly drowned, you may be able to save 
his life by doing artificial respiration. The way to do 
this is described on pages 144-146. 


EMERGENCIES 


ii 5 

Curiosity of a Crowd. — When a person is hurt, or is 
taken sick, those who are near by often crowd around 
him out of curiosity to see what is going on. This is the 
wrong thing to do, because it shuts off the fresh air from 
the injured person, and interferes with those who try 
to help him. When a person is hurt, do not rush to 
look at him, but keep away unless you are able to help. 
If a doctor or nurse is working over the injured person, 
you can do no good by looking on, but you are likely to 
do great harm. 

First Aid. — If you are near some one who is injured, 
you may be of great help in giving him first-aid relief. 
Obey the leader if some one is directing the relief; or 
assume the leadership yourself if no one else does so. 
Observe the injured person carefully and think what to 
do before you try to give first aid. 

There are always three things to look for and to think 
about in an accident to a person : first, what is called 
the shock of the accident; second, bleeding; and third, 
broken bones. 

Shock. — A person who falls, or is struck a hard blow, 
or is suddenly hurt in any way, usually feels dizzy, short 
of breath, and sick, and often does not know anything 
at all for a moment. This sickness is called shock. If 
a person is suffering from the shock of an accident, do 
not rub him, or shake him, or force him to swallow 
liquids, for these things may make the shock worse. 
Lay the injured person down on his back so that his 
heart and breathing may go on as undisturbed as 


EMERGENCIES 


116 

possible. While he is lying still, observe him for 
bleeding, broken bones, and other dangerous condi¬ 
tions. Send for a physician, but while waiting for him, 
do what you can for the person. 

Bleeding. — A great danger in an accident is that of 
bleeding from a cut or wound. A person may lose a 
cupful of blood without danger, but if he loses a pint, he 
will be weak and faint. Bleeding from a small wound 
usually stops within five minutes, for the blood clots, 
and closes the open tubes (p. 95). Bleeding from 
a large artery is dangerous, for the blood flows so 
swiftly that its stream washes away the clot as fast as 
it is formed. Bleeding from a vein usually stops itself, 
for the blood pressure in a vein is so small and the 
blood stream flows so slowly, that the clot remains in 
the tube. 

Five Experiments. — Bleeding comes from an open 
blood tube, and will stop if the tube is held closed by a 
pressure which is somewhat greater than the pressure of 
the blood in the tube. You can understand how and 
where to make the pressure if you do the following ex¬ 
periments : 

1. Learn to feel the pulse in the wrist. Grasp the 
right wrist of one of your companions and feel the pulse 
with the first two fingers of your right hand. The ar¬ 
tery in which you feel the pulse lies on the front, thumb 
corner of the wrist. 

2. While you are feeling the pulse with your right 
hand, press upon the artery with a finger of your left 



EMERGENCIES 



117 

hand placed an inch or two above the place where you 
feel the pulse. Notice that a little pressure stops the 
pulse, for it closes the tube of the artery. The same 
amount of pressure on a wound, or on the flesh 
around it, would stop the bleeding, even if a large 
artery were cut in two. 


Four Experiments with the Pulse 

A pulse shows that blood is flowing through the artery ; and no pulse shows that 
no blood is flowing. 1, Feeling the pulse in the wrist; 2, stopping the pulse by 
pressure on the artery near the wrist; 3, stopping the pulse by pressure on the 
main artery of the arm above the elbow; 4, stopping the pulse by means of a 

twisted handkerchief, or tourniquet. 

3. While you feel the pulse with the right hand, as 
before, grasp the arm of your companion above the elbow 
with your left hand, holding your fingers straight in 
order to press as far as possible around the arm. Shut 
the hand as tightly as you need to until you cannot feel 
the pulse in the wrist. Notice that you can easily close 







n8 


EMERGENCIES 


your hand firmly enough to stop the pulse. This pres¬ 
sure would be sufficient to stop all bleeding even if 
an arm were cut off. You could hold a bleeding arm 
in this way for an hour or two if you had to do so. 

4. Pass a handkerchief around the arm of your com¬ 
panion above the elbow, and tie it so loosely that you 
can put your fingers under it easily. Twist the hand¬ 
kerchief, and notice how hard you have to twist it in 
order that you cannot feel the pulse in the wrist. You 
do not have to twist it hard enough to cut into the flesh 
or cause pain. If the arm were cut below the elbow, it 
could not bleed, for no blood could flow beyond the 
handkerchief. A handkerchief or other band used in 
this way, as shown in the fourth picture on page 117, 
is called a tourniquet (toor'm-ket). 

5. ,Now untwist the handkerchief slightly until you 
can feel the pulse again, and hold it in that way for a 
moment or two. Notice that the veins become filled 
with blood, and that the arm swells and turns purple. 
The pressure on the veins keeps the blood from flowing 
out of the arm, but the arteries remain open and con¬ 
tinue to bring blood into the arm. If there were a 
bleeding wound on the arm below the elbow, the 
handkerchief would increase the bleeding because 
the veins and capillaries would be distended with 
blood. 

If you do these five experiments carefully, and under¬ 
stand their meaning, you will be able to stop any bleed¬ 
ing which you can reach with your hands. 


EMERGENCIES 




TI 9 

How to Stop a Bleeding. — If you wound yourself, or 
see another person bleeding, there are five things which 
you can do to stop the bleeding, all of which consist in 
making pressure upon the cut blood tubes. 


Stopping a Bleeding by Grasping 
the Sides of the Cut 

You can stop almost any bleeding by 
using your fingers or hands in the 
way shown here. 


Stopping a Bleeding by Pressing 
a Handkerchief upon the Bleed¬ 
ing Spot 

You do not need to make a painful pres¬ 
sure in order to stop the flow of blood. 


1. Grasp the flesh around the wound and press the 
sides of the wound together, so as to close all the blood 
tubes which go to the 
wounded place. You may 
need to use both hands if 
the wound is large; but if 
the wound is small, you can 
press directly upon the 
bleeding spot. 

2. Take a clean handker¬ 
chief or any piece of clean 
cloth and hold it firmly 
upon the wound. You may need to hold it for five or 
ten minutes, or until a firm clot forms in the blood tubes. 


Stopping a Bleeding by Binding a 
Handkerchief upon the Wound 


Make 


the binding handkerchief 
snugly and evenly. 


fit 









120 


EMERGENCIES 


3. Crumple a clean handkerchief into a pad and tie 
it upon the wound by means of one or two more 
handkerchiefs passed around the wounded limb. 

4. Grasp a bleeding arm or leg above the wound and 
shut your hands around it, just as you grasped the arm 
in the third experiment with the pulse (p. 117). You 
might need to do this if the wound is large and the flesh 
is badly torn. You will not need to squeeze the limb 
with great force, but you can easily hold the blood tubes 
closed a long time. 

5. Tie a handkerchief loosely around the limb and 
twist it in order to form a tourniquet as you did in 
the fourth experiment with the pulse (p. 118). By this 
means you can stop the bleeding if a hand or foot is 
cut off. 

A danger in the use of a tourniquet is that you may 
twist it so hard that it cuts into the flesh and causes 
pain. Another danger is that you may not twist it hard 
enough. If the tourniquet stops the flow in the veins 
but not in the arteries, it may even increase the bleed¬ 
ing (see the fifth experiment, p. 118). 

An Arm Sling. — When a wounded part has stopped 
bleeding, you need to keep it at rest in order to pre¬ 
vent disturbing the blood clot. If an arm is wounded, 
you can support it in a sling. 

Fold a large handkerchief, or a square yard of muslin, 
once, making a triangle. Place the middle point of the 
triangle under the elbow and bring the ends up over the 
shoulders and tie them behind the neck. 


EMERGENCIES 


I 2 I 



An Arm Sling 

Fold the cloth once in a triangle. Place the square angle under the elbow. 
Bring the ends up over the shoulders. The end lying under the arm goes over 

the shoulder opposite the supported arm. 

Nosebleed. — Blood in a bleeding nose nearly always 
comes from an open vein in the front part of the nostrils. 

If you have a nosebleed, you can stop it by holding 
your nostrils closed with your thumb and finger for 
about five minutes while you breathe through your 
mouth. This will close the vein and allow the blood to 
clot in it. 

Dressing a Wound. — When bleeding has stopped, a 
wound must be dressed in order to prevent disease germs 
from entering it. When a person is wounded in an ac¬ 
cident, you may have to use whatever dressing there is 
at hand. Clean handkerchiefs make good dressings, or 
pieces of cloth torn from a clean shirt or undergarment. 

Three common dressings which you can buy are: 

i. Gauze roller bandages, each io yards long. The 
best width is two and one half inches. 








122 


EMERGENCIES 


: 2. Sterilized gauze in packages of one yard each. 

3. Absorbent cotton in rolls, or packages, of various 
sizes up to one pound each. 

When you apply a first-aid dressing to a wound, 
crumple up some of the dressing so as to make a flat pad. 
Place the pad on the wound and bind it in place with a 
handkerchief or roller bandage. The pad of dressing, 

pressed upon the wound, 
will also help to keep 
the wound from bleed¬ 
ing. 

When you apply a 
first-aid dressing, there 
are three reasons why 
it is usually best not to 
wash the wound: 

1. You are likely to 
remove the blood clot 
and increase the amount of bleeding. 

2. You are likely to put dirt and disease germs into 
the wound. 

3. Blood itself is a good dressing for a wound. 

Disease Germs in Wounds. — A wound will usually i 

heal quickly and without pain or tenderness if no disease 
germs grow in it; but if disease germs are present, they 
keep the wound from healing and cause it to be red and 
sore. Redness and soreness in a wound and the skin 
around it are signs that disease germs are poisoning the 
wound. 



Bandaging an Arm with a Roller 
Bandage 


Lay the bandage obliquely so that both its 
edges are snug. , 






EMERGENCIES 


123 



When disease germs grow in a wound, the white blood 
cells attack them. But often many of the blood cells 
are killed by the germs. The white matter, or pus , 
which runs from sore wounds, pimples, and boils, con¬ 
sists of white blood cells which have died while they 
were defending the body against disease germs. 

The disease germs which grow in wounds are the 
same kinds as those in pimples and boils. They are 
scattered almost every¬ 
where, for pimples, 
boils, and small sores 
are common, and their 
germs are in most dirt 
of houses and streets. 

They may usually be 
found growing among 
the dead cells of epi¬ 
dermis on the surface 
of the skin, and are 
likely to enter every 
wound, unless great pains are taken to keep them 
out. 

One of the principal sources of disease germs in 
wounds is the skin itself. The best means of killing 
disease germs in the skin around a wound is iodine 
(Vo-din). When you are ready to dress a wound, wipe 
the blood from the skin around it and paint the skin 
with tincture of iodine. It will do no harm if some of 
the iodine gets into the wound itself. 


' k $£$:&&&. S' ft. 


% Uhtf 



Disease Germs That Grow in Wounds 

(Magnified 1000 times.) These are the kind 
that causes boils. 




124 


EMERGENCIES 


If you receive a small wound, such as a cut finger, 
paint it with iodine and wrap a clean dressing around it. 

Wet Dressings. — If a wound is already sore and 
disease germs are growing in it, or if the skin around a 
wound is dirty, you can kill the germs by using a dress¬ 
ing which is kept wet with clean water. When a dry 
dressing is used on a sore wound, the pus which runs 
from it dries and forms a crust or scab which holds the 
pus and disease germs in the wound. A wet dressing 
soaks up the pus and disease germs and removes them 
from the wound as fast as they are formed, and so it 
keeps them from poisoning the flesh. 

You can make a wet dressing by wetting a dressing 
every hour or two. Boil the water in order to kill all 
disease germs which may be in it. You can add a sub¬ 
stance, such as borax, which will help to kill the disease 
germs. 

All kinds of dressings which are sticky or greasy, such 
as sticking plaster, court-plaster, and salves, are usually 
harmful to a wound, for they keep the pus and other dis¬ 
charges from leaving the wound. 

Emergency Dressing Outfit. — Those who are camp¬ 
ing or traveling where they cannot reach a doctor 
quickly, need to carry a box of supplies for dressing 
wounds. The following is a good list for two or three 
persons to take: 

One package of absorbent cotton, -j- pound. 

Four gauze bandages, each two and one half inches 
wide. 



EMERGENCIES 


125 


Three packages of gauze, one yard each, for dressings. 

A glass-stoppered, half-ounce bottle of tincture of 
iodine. 

Scissors for cutting the dressings. 

These dressings will be enough for two or three 
wounds, and will enable you to give first aid in any 
wound which you are likely to see. 

Tetanus. — There is a disease, called tet'anus , or lock¬ 
jaw , in which the muscles of the whole body become con¬ 
tracted, beginning with those of the lower jaw. The 
disease is caused by disease germs which often grow in 
the intestines of horses and cattle, and are often found 
in street dirt and the soil of cultivated fields. They do 
not grow in wounds which the air can reach, but they 
often grow in deep wounds which the air cannot enter, 
such as those made by dirty splinters and nails which 
carry the germs deep into the flesh. The germs may 
grow beneath burned flesh, as in wounds made by fire¬ 
crackers. The disease is severe and painful, and often 
produces death. 

Tetanus may be prevented, and usually cured, by the 
use of tetanus antitoxin. A hypodermic injection is 
given into the skin when the wound is first dressed. 
Many boards of health supply the antitoxin free to be 
given to those who are wounded or burned deeply. 

Broken Bones. — When a person has been hurt, try 
to find out whether or not his bones are injured. A 
broken bone is not dangerous to life unless it sticks 
through the flesh, but it is always painful. Sprains, 



126 


EMERGENCIES 


and bones out of joint, are also painful, but not danger¬ 
ous to life. 

You may lessen the pain of a sprain, or of a bone out 
of joint, by bandaging a stick or thin board to the limb 
in such a way that it keeps the injured part at rest 
(p. 77). Then the person may be moved with com¬ 
fort and safety. 

Fainting. — A person who is weak, or sick, or hurt, 
or frightened, sometimes looks pale, feels dizzy, and 
falls down and knows nothing for a few seconds. We 
then say that he has fainted. What has happened is 
that the heart has suddenly become weak and has 
failed to send blood to the head, and the mind has 
stopped acting for a moment. 

When a person faints, lay him down and keep his 
head low, so that blood will flow to it. Rub his body, or 
throw cold water into his face, so as to rouse him. In 
a moment his heart will begin to beat strongly, and he 
will soon feel well again. 

Fits and Convulsions. — Sometimes a person sud¬ 
denly falls down, his arms and legs stiffen and shake, 
and his face twitches as if he were in pain. We then say 
that he has a jit , or convuVsion. The stiffness and 
twitching are caused by contractions of most of the 
the muscles of the body. While a person is in a fit, 
he knows nothing and does not suffer. 

A fit in a grown person is usually caused by a brain 
trouble called ep'ilepsy. While a person is in a fit of 
epilepsy, almost the only immediate danger is that he 




EMERGENCIES 


127 


may bite his tongue or cheeks. You may prevent this 
by pressing a handkerchief into his mouth, so as to 
keep the tongue away from the teeth. You can do 
nothing to bring a person out of a fit, but in a minute 
or two the fit usually passes off, and the person feels 
well again. 

A fit in a baby is usually caused by spoiled food in its 
digestive organs, and usually stops when the cause is 
removed. 

Hysterics. — There is a kind of fit, called hyster'ics, 
in which a person laughs and cries, and also moves the 
body as in a real fit. But the person who has hysterics 
knows what is going on, while in a real fit he knows 
nothing at all. Hysterics are usually caused by fear, 
or worry. The person who has them acts like a spoiled 
child that throws itself on the floor, and kicks and cries. 

There is no danger from hysterics. Keep yourself 
calm and cool-headed, and act toward the sick person 
just as you would toward a spoiled child. 

QUESTIONS 

Name some of the principal causes of accidents to persons. 

Name some important topics in studying about safety first. 

Name some important measures of fire protection. 

What is a panic f 

Of what use are fire drills at school? 

Give some reasons why every boy and girl should learn to swim. 

Why is it harmful to an injured person for a crowd to gather around 
him? 

What is meant by shock due to an accident ? 

What should you do for shock ? 

Where can you feel the pulse easily ? 


128 


EMERGENCIES 


How can you stop a bleeding wound with your bare hands ? 

How should you apply a dressing to a wound in order to stop its 
bleeding ? 

How should you apply a tourniquet to stop a bleeding wound ? 

How should you dress a wound ? 

How and why should you apply iodine to a wound ? 

Describe a wet dressing. When should it be used ? 

How should you stop a nosebleed ? 

How should you help a person who has a broken bone? 

What condition of the circulation causes a person to faint? 

How should you help a person who is faint? 

What is a fit? 

What should you do to help a person who is in a fit ? 

How can you tell hysteric* from a real fit? 

What should you do for a person who has hysterics ? 

For the Teacher. — An emergency is an unexpected or unfamiliar condition. 
Anticipate the common conditions in which panics occur, and drill the pupils 
in simple methods of meeting them. 

Panic is best prevented by the discipline of fire drills. Children who fre¬ 
quently take part in fire drills are likely to be cool and thoughtful in any 
emergency. A special point to be emphasized is the danger of collecting in 
crowds out of curiosity at fires and accidents. 

Emphasize the danger of doing too much for a person in a shock. Do not be 
misled by outcries of an injured person. One who is making a noise and tossing 
his body about is probably more frightened than hurt, for a badly injured person 
is likely to be dazed or unconscious. 

Always examine an injured person for the appearance of blood. If a bleeding 
spot is found, grasp it at once boldly and hold it fast, so as to stop the flow of 
blood. Remember that a tourniquet is the last means to try in stopping a bleeding, 
and that it cannot be applied to many parts, such as the head, neck, and trunk. 

Do not burden the pupils with distinctions between venous and arterial 
bleeding. The same methods will stop either kind. 

Demonstrate the method of applying a first-aid dressing to a wound. 
Emphasize that there is danger of infecting a wound by attempts to clean 
it, and that blood itself, bound upon a wound, is nature’s own effective cleans¬ 
ing agent. 

Demonstrate also the method of applying a wet dressing, and its very great 
value in killing disease germs at their very entrance into the wound. Emphasize 
the value of iodine in treating small wounds. 


CHAPTER XI 


RESPIRATION 

Respiration and Oxidation. — Several pounds of 
substances enter the body each day, and yet the body 
increases its weight only slightly, for the amount of 
substances which leaves it is almost equal to the amount 
which enters it. The substances which enter the body 
are food and oxygen. These substances are built into 
flesh and blood, and then are given off from the body in 
the form of carbon dioxide, water, urea, and other 
waste substances which are formed by the process of 
oxidation (p. 34). The process of taking and using 
oxygen by the living body is called respiration. A 
complete act of respiration is done in four steps: 

1. Breathing, or taking oxygen into the body. 

2. Carrying the oxygen through the body by means 
of the blood. 

3. Oxidation. 

4. Removing the oxidized substances. 

The Lungs. — The first step in respiration is that of 
breathing, or taking oxygen into the body. The oxy¬ 
gen is taken from the air by means of organs, called 
lungs , which are composed of millions of tiny, thin- 
walled air sacs. Air enters the sacs by passing from 
the nose through a tube, called the windpipe , or 


OV. GEN. HYG.- 9 


129 



130 


RESPIRATION 




Frog’s Lung 

(Natural size.) It is a thin bag 
with shallow partitions. 


trachea (tra'ke-a). This divides again and again 

into branches, called bronchi 
(brong'kl), the smallest of 
which end in the air sacs. 
The air sacs and branches 
are like bunches of hollow 
grapes hanging from hollow 
stems. 

The structure of a human 
lung may be illustrated by 
the lungs of a frog and of a 
turtle. 

A frog’s lung is a thin- 
walled sac, about the size 
of the last joint of a persons finger. Its inner surface 
is marked off into 
shallow spaces with 
low partitions over 
which arteries and 
capillaries run. The 
whole lung is like a 
single air sac in a 
human lung greatly 
magnified. 

A turtle’s lung is 
divided into a great 
number of large air 
spaces by thin walls 
which extend in every 


Turtle’s Lung 

(Natural size.) It is crossed by partitions 
running in every direction; and is like a 
magnified bit of human lung. 





RESPIRATION 


131 


direction through the lung. Each air space is like an 
enlarged air sac in a human lung. 

Breathing. — The lungs hang in the bony box called 
the chest , or tho'rax , whose sides are formed by the ribs, 
and the bottom, by a dome-shaped sheet of muscle, 
called the diaphragm (dl'a-fram). When the ribs 
are raised, or the diaphragm flattened, the chest be¬ 
comes larger and sucks air into the lungs. When 
the chest muscles relax the chest becomes smaller, 
and expels air from the lungs. The passing of air into 
and out of the lungs is called breathing. Taking air 
into the lungs is called inspiration , and forcing out 
the air is called expiration. A person usually breathes 
fifteen or twenty times each minute. 

- The second step of respira- 


The Red Blood Cells. 

tion is that of carry¬ 
ing oxygen through all 
the body. The inside 
of each air sac is cov¬ 
ered with a close net¬ 
work of capillaries. 

As the blood flows 
through the capilla¬ 
ries, its red cells take 
up oxygen from the air 
sacs, and they then 
carry it through the 
arteries to all parts of 
the body. The oxygen which the red cells carry 



Capillaries on the Inside of Air Sacs 

(Magnified 500 times.) Capillaries are closer 
together here than in any other part of the 

body. 






132 


RESPIRATION 


makes the blood in the arteries bright red in color. 
The red blood cells take up about one and a half 
pounds of oxygen from the air sacs every day. 

As the red blood cells pass through the capillaries 
of the muscles and other organs, they give their oxygen 
to the living parts that need it. The blood which flows 
back to the heart is dark red in color because it lacks 
oxygen. 

A fish gets its oxygen from the air which is dissolved 
in the water. Its gills are like combs whose teeth pro¬ 
ject into the water. Red blood cells, passing through 
the capillaries in the gills, take up oxygen from the 
water. A fish breathes by opening and shutting its 
mouth in order to keep a fresh supply of water running 
over its gills. 

Oxidation. — The third step in respiration is the 
oxidation in the living cells. Some oxidation takes place 
with nearly ever} 7 act which a cell does. Muscles use 
more oxygen than any other group of cells. When 
muscles do hard work, they quickly use all the oxygen 
which the red blood cells can bring to them. Breath¬ 
ing then becomes rapid and deep, and the heart beats 
hard and fast in order to carry more oxygen to the 
muscles. When the muscles have used all the oxygen 
that they can get, the strength fails, and a person has 
to stop exercising. 

Carbon Dioxide. — The fourth step in respiration is 
that of removing the oxidized substances from the 
body. Anything which has been fully oxidized is 



RESPIRATION 


133 


usually of no further use to the body, but is a waste 
substance which the body throws off. One of the prin¬ 
cipal waste substances of the body is carbon dioxide 

(P- 34 )- 

The blood, passing through the capillaries in all 
parts of the body except the lungs, takes up carbon 
dioxide and carries it to the lungs, and there gives it 
off to the air in the air sacs. The carbon dioxide then 
passes out from the body with the breath of the next 
expiration. 

Summary of the Changes Produced by Breath¬ 
ing. — During inspiration, the lungs receive oxygen. 
During expiration, the lungs give off carbon dioxide. 

The air sacs of the lungs give oxygen to the blood, 
and receive carbon dioxide from it. 

In the lungs the blood takes oxygen, and gives off 
carbon dioxide. 

In the capillaries of the body the blood gives off 
oxygen and takes up carbon dioxide and other waste 
substances. 

The cells of the body take oxygen from the blood, 
and give carbon dioxide and other oxidized substances 
to it. 

The Objects in Respiration. — Respiration is car¬ 
ried on for two objects : 

1. To produce the heat which warms the body. 

2. To produce the power which drives all the ma- 
chinery of the body. 

The body needs power to carry on every movement, 


134 


RESPIRATION 


thought, or other action of its machinery. This 
power comes from the oxidation which takes place 
while the action is going on. If any one of the four 
steps of respiration is done imperfectly in your body, 
you feel dull, lazy, and weak. But when oxidation 
takes place in a perfect manner, you feel bright and 
active, you enjoy your work and play, and your whole 
body is strong and vigorous. 

Breathing and Health. — You can increase your 
strength and endurance, as well as your health, by do¬ 
ing those things which will help the oxidation in your 
body. There are two principal ways of doing this: 

1. By taking exercise. 

2. By practicing deep breathing. 

Exercise and Oxidation. — Most of the oxygen which 
enters the body is used by the muscles. When the 
muscles are at rest, the body uses little oxygen; but 
when you take exercise, your muscles use much oxy¬ 
gen, and you feel short of breath and have to breathe 
deeply. During exercise the body uses four or five 
times more oxygen than while it is at rest. Exercise 
also starts up all the other actions of the body 

(p. 88). 

Deep Breathing. — If you have to sit still for hours 
and have but little time for exercise, you can increase 
the oxidation in your body by taking deep breaths 
often. When you begin to feel dull, sit up straight, 
take a deep breath, and hold it while you throw your 
shoulders back. This will stretch the air sacs of your 




RESPIRATION 


135 



lungs wide open, will fill them with a large amount of 
oxygen, and will make you feel bright and active. 

Lung diseases may be caused by disease germs which 
enter the lungs with impure air. If the lungs do not 
receive a large quantity of air, the disease germs will 
lie quiet in the air 
sacs and the smaller 
air tubes, and will 
grow there undis¬ 
turbed. But deep 
breathing will stir up 
the germs and drive 
them out of the lungs. 

The movements of 
breathing will cause 
the blood to flow freely 
among all the air sacs, 
where its white blood 
cells will destroy the 
disease germs which 
may enter the sacs. 

Deep breathing is one 
of the best of all means for preventing lung diseases 
and promoting health. 

Measurement of Breathing. — There are two easy 
ways of measuring the quantity of air which you take 
into your lungs. One way is by passing a tape measure 
around your chest under your arms and noting the size 
of your chest before taking a breath, and again after 


Measuring the Expansion of the 
Chest 

An expansion of less than two inches is small 
for a twelve-year-old boy. 







i 3 6 


RESPIRATION 


taking it. An expansion of three inches is large for a 
twelve-year-old boy. An expansion of less than two 
inches is too little for him. 

Another way of measuring the air which you breathe 

is to fill a large glass jar 
with water and turn it 
upside down in a shallow 
pan of water in such a 
way that the water re¬ 
mains in the jar. Then 
pass a rubber tube under 
the water into the jar, and 
blow through it. As air 
enters the jar, the water 
passes out. By measur¬ 
ing the distance the water 
sinks in the jar you can 
tell how much air you 
breathe out from your lungs. 

When a man sits still at a desk and breathes quietly, 
he expands his chest about half an inch, and inhales 
about thirty cubic inches, or a pint, of air with each 
breath. When a strong man takes a very deep breath, 
he expands his chest four or five inches, and inhales 
from two to four quarts of air. 

A single deep breath of air will last your body less 
than a minute. You cannot store oxygen in your 
body, but you must take it into your body at the 
moment when you need to use it. 



Collecting the Air Blown from 
the Lungs, So That It Can Be 
Measured 

As air is blown into the bottle, water 
leaves it. 







RESPIRATION 


137 


QUESTIONS 

What is respiration? 

What are the four steps in a complete act of respiration? 

Describe the lungs. 

Describe the process of breathing. 

How is oxygen carried through the body? 

Describe the process of oxidation in the body. 

Describe the process of getting rid of oxidized products. 

What are the objects of respiration? 

By what means can you promote oxidation in your body? 

How does exercise promote vigor and health ? 

How does deep breathing promote health ? 

How can you measure the amount of air which you can breathe 
into your lungs ? 

How many inches should a twelve-year-old boy be able to expand 
his lungs ? 

For the Teacher. —In this chapter the subject of oxidation is discussed from 
the standpoint of the intake of oxygen. In the next chapter and Chapter XXII 
it is discussed from the standpoint of the intake of food. The processes of 
nutrition and oxidation are closely related, and each must be understood in 
order to understand the other. 

Emphasize the four steps in a complete act of respiration as described in 
the text. 

Practical hygienic applications of the subject of respiration are made in 
the topics of deep breathing and of exercise. 

Emphasize the relation of exercise to respiration. Since most of the oxygen 
which enters the body is used during muscular action, exercise of the muscles 
is about the only practical means of increasing or controlling respiration. This 
explains the great value of exercise in maintaining a high degree of efficiency 
in the actions of the body. 

Demonstrate the methods of estimating the efficiency of breathing by 
measuring the expansion of the chest, and the quantity of air which can be 
expired from the lungs. 


CHAPTER XII 


HINDRANCES TO BREATHING 


Balance of Food and Oxygen. — Good health de¬ 
pends upon a proper balance between the amount of 
food and the quantity of oxygen which are taken into 
the body. The weight of oxygen which a person needs 

in a day is about one and a half 
times the weight of his food (ex¬ 
clusive of water). The protein, 
sugar, and fat which the body of 
a grown person takes each day 
weigh about 16 ounces; but the 
oxygen which is needed to oxidize 
the food is about 24 ounces. Eat¬ 
ing more food than the body 
Weights of Oxygen and • j. . r .1 

of Food can oxidize is one 01 the greatest 

The oxygen used in the body hindrances to proper respiration, 
protein, sugar, and fat that are E the aniOUllt of Oxygen is not 

oxidized. sufficient to oxidize the food, the 

waste substances are only partly formed, and are 
harmful and poisonous, like the smoke of a lamp that 
burns poorly. Imperfect oxidation, or sub oxidation, 
causes diseases of the kidneys, dullness of the mind, 

138 





HINDRANCES TO BREATHING 


139 


and sickness of the stomach. It also causes the body 
to become fat, because some of the food and flesh 
are not oxidized. 

There are two means of preventing or curing suboxi¬ 
dation : 

1. By increasing the amount of oxygen which is 
taken into the body. 

2. By decreasing the amount of food. 

The only way to increase the intake of oxygen volun¬ 
tarily is to take exercise. If a large amount of food is 
eaten, it will be oxidized if hard exercise is taken. But 
many persons cannot take exercise because they sit 
still all day at their work. These persons will oxidize 
their food well if they take no more than can be oxi¬ 
dized by the oxygen which they breathe. If, for ex¬ 
ample, a person sits still all day and takes only 16 
ounces of oxygen into the body, he can oxidize about 
10 ounces of food and no more. Adjusting the amount 
of food to the amount of exercise is one of the best 
means of keeping the body healthy and the mind active. 

There are two types of persons in regard to their 
intake of food and oxygen. The first type consists 
of those whose chests and lungs are large, and their 
stomachs small. A person of this type takes a great 
deal of oxygen into his body, but his stomach is unable 
to digest as much food as the lungs can oxidize. He is 
likely to be active and to do much hard work; but 
he will not grow fat because he oxidizes his food and 
flesh well. He will usually be long-winded, and will 


140 


HINDRANCES TO BREATHING 


seldom have lung troubles, but he may suffer with in¬ 
digestion because his stomach will often be overworked. 
This type of person is not likely to overeat, but he needs 
plenty of food which can be easily digested. 

The second type of person has small lungs and a large 
stomach. He can easily digest more food than the 
lungs can oxidize, and so he grows fat. He seldom 
has indigestion, but he is often short of breath, and is 
subject to lung diseases and the troubles which go with 
suboxidation. He is also likely to have diseases of the 
kidneys, because the wastes of his body consist of half- 
oxidized substances which are poisonous. A person of 
this type should eat food which is not easily digested, 
in order that the small amount of food which reaches 
his blood may be fully oxidized. 

Stooped Shoulders. — Stooped shoulders are great 
hindrances to breathing. If you allow your shoulders 
to fall forward, their weight and the weight of your 
arms will press upon your chest, and you will be un¬ 
able to breathe freely. Take as deep a breath as you 
can while you sit with your shoulders bent forward and 
resting on your chest. Then throw your shoulders 
back and see how much more air you can take into 
your lungs. 

When you sit up straight, the muscles of your back 
will hold your shoulders up, and will also help to raise 
the ribs when you take a deep breath. When you 
bend over your work, do not let your shoulders fall 
forward on your chest. Keep them thrown back and 



HINDRANCES TO BREATHING 


141 

your elbows at your side. You will then be able to 
breathe freely, even though you have to bend forward 
while you work. 

Tight Clothing. — Tight clothing is also a great 
hindrance to breathing. If your clothing is tight, 
you cannot move your 
chest freely, and can¬ 
not breathe deeply. 

Half of the move¬ 
ments of breathing 
are done by flatten¬ 
ing the diaphragm 
and moving the parts 
of the body below 
the waist line. Tight 
clothing around the 
waist interferes with 
breathing almost as 
much as it would if 
it were around the 
chest. 

Mouth Breathing. 

The lining of the nose is crumpled into folds, and 
is moistened with mucus. As air passes over the folds, 
it is warmed and moistened, and most of the dust and 
disease germs which may be in it is caught in the 
mucus. If the air passes through the mouth, it enters 
the lungs cold and dusty. Mouth breathing is harmful 
to the lungs, and is the cause of a great deal of ill health. 



Folds inside of a Calf’s Nose 
A man has the same kind of folds in his nose. 





142 


HINDRANCES TO BREATHING 


Every person will naturally breathe through his nose 
if it is clear and open. If he breathes through his 
mouth, it is because his nose is partly stopped up. 

A stopped-up nose 
always feels un¬ 
comfortable, and 
breathing through 
the mouth requires 
an effort. A child 
at school cannot 
put his mind upon 
his lessons if he has 
to think about his 
breathing every 
moment. 

Your nose may 
be stopped up with 
mucus. If this is so, 
remove the mucus 
by blowing it out. 

If your nose remains stopped up after blowing it 
lightly two or three times, the stoppage is probably 
caused by a swelling of its lining. This swelling is 
usually due to an extra amount of blood in the nose. 
Blowing the nose hard will send more blood to it, and 
will make the swelling worse. You can make the swell¬ 
ing go down by blowing out all the breath that you can, 
and then waiting as long as you can before you take 
another breath. The chest, in trying to expand, will 



Model of the Nose and Throat 

It shows how the nose and throat would look in¬ 
side if the head were opened in halves. 









HINDRANCES TO BREATHING 


143 


draw blood away from the head. The blood tubes of 
the nose will then be emptied, and the swelling of the 
lining will go down. 

Adenoids. — Mouth breathing is often caused by 
masses of soft flesh, 
called adenoids 
(ad'e-noidz), grow¬ 
ing in the back 
part of the throat 
behind the nose. 

Children who hold 
their mouths open 
while they breathe, 
and who snore in 
their sleep, nearly 
always have ade¬ 
noids. What is 
called catarrh is usu¬ 
ally due to adenoids. They are often the cause of colds, 
sore throats, and deafness. They can be removed as 
quickly, safely, and painlessly as a tooth can be pulled. 
Their loss does not produce any bad effects, for they 
are of no use to the body. After a child has had his 
adenoids removed, there is nearly always a remarkable 
improvement in his health, strength, and appear¬ 
ance. 

Enlarged Tonsils. — Two round masses of flesh, 
about the size of walnuts, may extend from the 
sides of the throat and almost meet over the back of 



Adenoids and Tonsils 

(Natural size.) These were taken from the throat 
of a three-year-old boy. The lower figures are 
tonsils which contain many holes. 






144 


HINDRANCES TO BREATHING 


the tongue. These masses are called enlarged tonsils. 
They interfere with breathing and speaking, just as if 
marbles were held in the throat. They are nearly 
always full of holes in which disease germs often lodge 
and grow, producing the bad form of sore throat called 
tonsillitis. Those who have enlarged tonsils nearly 

always have ade¬ 
noids. The tonsils 
may be removed 
with as much ben¬ 
efit as adenoids. 

Artificial Respi¬ 
ration.— A person 
who has been 
nearly drowned 
may be brought 

The Schaefer method. Press upon the ribs to force back tO life by 
the air out of the lungs. 

causing air to pass 
into and out of his lungs, as in natural breathing. 
Causing a person’s chest to move in imitation of nat¬ 
ural breathing is called artificial respiration. If you 
know how to do artificial respiration, you may be able 
to save the life of a half-drowned person when no one 
else is near. 

Nearly all methods of doing artificial respiration 
depend on the elasticity of the walls of the chest. The 
ribs lie naturally in a position halfway between inspira¬ 
tion and expiration. Pressing upon the ribs reduces 
the size of the chest, and expels air from the lungs. 






HINDRANCES TO BREATHING 


!45 


When the ribs are released, they spring up and produce 
an inspiration as in natural breathing. 

A standard method of doing artificial respiration is 
as follows: 



Place the nearly drowned person on the ground 
or floor with one 
arm above his 
head and the elbow 
bent. Rest his 
head upon the 
forearm with his 
face turned away 
from his elbow. 

Kneel astride 
the person’s thighs, 
facing his head. 

Place your hands 
upon the body, one on each side, just over the lowest 
ribs. 

Bend forward and bear the weight of your body 
upon your hands as they press upon the ribs (picture 
on page 144). This produces an expiration. Hold this 
position long enough to say, “ Out goes the water.” 

Suddenly press forward with your arms and throw 
your body upright, lifting your hands from the ribs 
(picture above). As you lift the hands, you can hear 
air rush into the lungs. Remain in the upright position 
long enough to say, “ In goes the air.” 

Make these two motions as often as you repeat the 


Artificial Respiration, — Inspiration 

Stopping the pressure lets the ribs spring up and 
suck air into the lungs. 


OV. GEN. HYG. — IO 









146 


HINDRANCES TO BREATHING 


two sentences in a natural way. Bend forward as you 
say the word “ Out,” and sit upright when you say 
the word “ In.” 

Continue the movements until the person breathes 
naturally, even if it takes an hour or two. 

Practice these movements on a companion, and let 
him do them on you. If you do this, you will know how 
to do the movements when there is need, and will also 
learn how to avoid using a harmful amount of force. 

A pulmotor is a machine for doing artificial respira¬ 
tion, but it is no more efficient than the method just 
described. If you have the opportunity to help a 
drowned person, begin to do artificial respiration at 
once, without waiting for a pulmotor or a doctor. 

Electric Shock. — If a person has received a strong 
shock of electricity, his life is in danger because he can¬ 
not breathe. You may be able to save his life by do¬ 
ing artificial respiration. 

Alcohol and Oxidation. — Alcohol will readily unite 
with oxygen and will burn with a hot flame. An 
alcohol lamp burns alcohol which is drawn up a cotton 
wick. The wick hardly burns at all, for oxygen unites 
with the alcohol instead of the cotton of the wick. 

When alcohol enters the body, it becomes oxidized 
quickly, and uses up the oxygen which would otherwise 
oxidize food and flesh. Therefore its use deprives the 
body and its food of oxygen and produces the same 
harmful effects that breathing too little oxygen will 
produce. 


HINDRANCES TO BREATHING 


147 


QUESTIONS 

What is the weight of food which is taken into the body daily? 
What is the weight of the oxygen? 

What is suboxidation? 

How may wrong eating interfere with respiration ? 

What has oxidation to do with the stoutness or thinness of a 
person ? 

How do stooped shoulders interfere with breathing? 

How does tight clothing interfere with breathing? 

How long will a deep breath of air last the body ? 

What harm comes from breathing through the mouth? 

What are three common causes which prevent a person from 
breathing through the nose? 

How can you cause your nose to become open when it is stopped 
up? 

What are adenoids? 

What harm do adenoids do? 

How can you get rid of adenoids ? 

What are enlarged tonsils? 

What harm do enlarged tonsils do? 

How can you save the life of a person who is nearly drowned ? 

Describe the method of doing artificial respiration. 

What would you do for a person who has received a bad shock of 
electricity ? 

What effect does alcohol have on the oxidation in the body ? 

For the Teacher. — This chapter discusses some common causes of deficient 
oxidation and the means of overcoming them. A great cause of ill health, 
especially among grown persons, is deficient oxidation due to the intake of too 
much food or too little oxygen. Show the possibility of remedying the con¬ 
dition by either eating less food or taking more exercise. 

Discuss mouth breathing and the common causes of a stopped-up nose. 
Adenoids and enlarged tonsils do great harm by causing mouth breathing, but 
they do still more by being sources of infection as described in Chapter XXV. 

Demonstrate the Schaefer, or prone, method of doing artificial respiration 
as described in the text. Emphasize the need of making the motions with 
the frequency with which the sentences given are naturally spoken. A com¬ 
mon fault in doing artificial respiration is that of hurrying so much that there 
is no time for the oxygen which enters th * Jungs to be absorbed. 


CHAPTER XIII 


FOUL AIR 

Composition of Air. — The air which is breathed into 
the lungs undergoes changes which make it unfit to be 
breathed again. Outdoor air which is fresh and whole¬ 
some is about 20 per cent oxygen, nearly 80 per cent 
nitrogen, and ywo P er cen t car b° n dioxide. It usually 
contains only a small quantity of vapor of water, and 
is cooler than the body. Fine particles of dust and a 
few bacteria and mold spores are nearly always floating 
in it. 

Breathing takes away some of the oxygen from the 
air and puts carbon dioxide in its place. Air which 
leaves the lungs is about 16 per cent oxygen, nearly 
80 per cent nitrogen, and 4 per cent carbon dioxide. 
The quantity of carbon dioxide which is added to the 
air nearly equals the quantity of oxygen which is taken 
from it. 

Air which is breathed out from the lungs is usually 
warmer than that which enters the lungs. It is loaded 
with vapor of water, and contains a small quantity of 
substances which give it a bad odor. The changes 
which breathing produces in the air are shown in the 
following table: 


148 




FOUL AIR 


149 


Substances and Qualities 
of the Air 

Inspired Air 

Expired Air 

Nitrogen (and other gases) 

Nearly 80 per cent 

Nearly 80 per cent 

Oxygen . 

__ t < <( 

20 

16 " “ 

Carbon dioxide .... 

4 ll cc 

100 

- “ “ 

4 

Moisture. 

Usually dry 

Very moist 

Odor. 

Usually none 

Considerable 

Warmth. 

Usually cool 

Warm 


Breathing has no effect on the nitrogen of the air. 
Pure oxygen acts in a manner which is tod rapid and 
forcible for health. When the red-hot end of an iron 
wire is thrust into a jar of oxygen, the wire burns like 
a match and throws oh showers of sparks. If a stove 
were set up in a room full of oxygen, its iron would 
burn up if a fire were started in it. The use of the ni¬ 
trogen of the air is to dilute the oxygen and make it 
act in a mild way. 

How Air is Made Impure. — The changes in air 
which are produced by breathing are like those which 
are produced by a fire. Since fires, animals, and per¬ 
sons are always using up oxygen and pouring carbon 
dioxide into the air, it might be supposed that the out¬ 
door air would finally become impure. It does not do 
so, for two reasons: first, the winds carry the impuri¬ 
ties away and bring in fresh air; and secondly, plants 
take carbon dioxide from the air and use it as food. 
Their green leaves separate the carbon from the oxy¬ 
gen. They give the oxygen back to the air, and use 
the carbon in building up their stems, roots, fruit, and 
















FOUL AIR 


150 

other growing parts. The quantity of oxygen which 
plants give to the air nearly balances the amount of 
oxygen which fires, lower animals, and persons take 
from the air. 

Danger from Lack of Oxygen. — Air which is 
breathed out from the lungs may still support life, 

but it may not contain 
enough oxygen to sup¬ 
port a fire, as the 
following experiments 
show: 

Wind the end of a 
wire around a piece of 
small candle, such as 
is used on Christmas 
trees. Light the candle 
and lower it into a pint 
jar. It will burn about 
ten seconds and will 
then go out, because 
the oxidation, or burn¬ 
ing, uses up the oxy¬ 
gen. 

Remove the impure air by filling the jar with water 
and then emptying it. Take a deep breath, hold it 
for about fifteen seconds, and blow it into the jar. 
Lower the lighted candle into the jar, and it will go 
out at once, because much of the oxygen was removed 
while the air was in the lungs. 



A Burning Candle in a Jar 

Experiment to show the amount of oxygen 
needed to support a fire. 



FOUL AIR 


151 

Cleanse the jar as before, take half a dozen deep 
breaths, and quickly blow the last one into the jar. 
Lower the lighted candle into it, and it will burn very 
nearly as long as it did in the first experiment, because 
the lungs did not have time to take much oxygen from 
the air. 

The air in wells, cellars, tunnels, and other closed 
places sometimes contains too little oxygen to support 
life, and persons have been suffocated on going into 
them. You can test the air of such a place by lowering 
a candle into it. If the candle continues to burn, there 
is enough oxygen in the place to support life; but if 
the candle goes out, the place may be dangerous to life. 

Foul Air in Living Rooms. — When the air of an 
ordinary living room is breathed over and over, it be¬ 
comes noticeably foul, and a person who breathes it is 
likely to be dull and short of breath, and to have a 
headache. If the air becomes very foul, he feels dizzy 
and faint. When the air of a schoolroom begins to be 
foul, the bad effects on everybody in the room quickly 
appear. The pupils become restless and irritable, and 
cannot put their minds to their work, or think clearly. 
They therefore often fail in their lessons. 

Breathing foul air day after day has a bad effect 
on the whole body. Many persons are weak, pale, and 
sickly because they breathe foul air during some part 
of the day or night. Fresh air, full of oxygen and free 
from the waste matters of the body, is necessary for 
health and strength. 


FOUL AIR 


1 5 2 

A person who is shut in a small, air-tight room, such 
as a bank safe, would soon use up the oxygen and 
would be in danger of his life. But breathing the 
air of an ordinary living room usually cannot use up 
enough oxygen to make the air dangerous to life, 
because the quantity of oxygen in the room is large, 
and because fresh air can enter the room through 
cracks in the floors and windows. The bad effects of 
foul air in living rooms, meeting places, and work¬ 
rooms are due chiefly to four principal causes: 

1. A warm temperature. 

2. Unpleasant odors. 

3. Dust. 

4. Disease germs. 

Effects of Warmth. — Experiments have been made 
with students who have worked for hours in small, 
air-tight rooms in which the air has been analyzed and 
all its impurities discovered and measured. It has 
been found that the principal condition which produces 
the unpleasant feelings of foul air is heat. When a 
crowd goes into a room which is comfortably warm, 
their bodies warm the air still more, as if the persons 
were radiators ; and the vapor of water in their breaths 
makes the air as damp as it is on a hot, foggy day in 
summer. The feelings produced by the warm, moist 
air of a close, crowded room are like those which are 
felt on a still summer day when not a breath of air 
is stirring. The experiments with the students showed 
that the unpleasant feelings produced by the close 


FOUL AIR 


*53 


air could be relieved or prevented by keeping the air 
in motion, as by an electric fan, even while the air re¬ 
mained foul. The effect of the moving air is to cool 
the body as is done by a hand fan. 

A comfortable temperature for a living room or meet¬ 
ing place is between 65° and 70° Fahrenheit. If the 
temperature goes above 75 0 F., the feelings which go 
with foul air usually appear, whether the air is foul 
or not. 

Odors. — Air that has been made foul by breathing 
has an unpleasant odor which comes from the human 
body. There is a peculiar odor of the human body, 
just as there is one of a horse, and another of a dog. 
These odors become noticeable when the air is close 
and warm. The substances to which the unpleasant 
odors are due are not harmful in themselves, but the 
odors make a person feel uncomfortable, and do harm 
by preventing one from thinking and resting. The 
odors are given off from the bodies of persons who are 
clean as well as from those who are dirty. Perfumes 
and incense do not destroy the foul-smelling substances 
in the air, but they act by adding other odors which 
are stronger than the unpleasant ones. The only way 
to prevent the unpleasant odors in a living room or 
meeting hall is to change the air of the room often. 

Moisture in Foul Air. — Expired air contains nearly 
all the vapor of water that it can hold. When the air 
is cold, the water in the breath looks like steam. Air 
that has been made foul by breathing is loaded with 


154 


FOUL AIR 


vapor which comes from the lungs. This vapor in¬ 
creases the bad odor of the air and the unpleasant 
feelings which are produced by the foul air. If the 
windows of a crowded room are wet with moisture 
which is produced by breathing, that air is too foul to 

be breathed with safety. 
Outdoor Dust. — 



Outdoor air always con¬ 
tains dust even over 
the ocean and on high 
mountain tops. Micro¬ 
scopic bits of dust in 
the air may be useful. 
A bit of dust is at the 
center of each raindrop 
and particle of water in 
a fog or cloud. If there 
were no dust in the 
air, there would be no 
gentle rains. But a large 
amount of fine dust par¬ 
ticles, such as those of smoke, may cause dense fog. 

Indoor Dust. —- The air of living rooms, meeting 
places, and workshops often contains a great amount 
of dust. There are three kinds of dust, according to 
their effects on health: 

1. The soft. 

2. The hard and sharp. 

3. The poisonous. 


House Dust 

(Magnified 200 times.) The fibers are 
cotton, and the rest of the dust consists 
mostly of bits of wood and ashes. 






FOUL AIR 


1 S5 


The dust in the air of living rooms and meeting 
halls usually consists of such substances as soil, ashes, 
and shreds of wood, cotton, and wool. These dust 
particles are nearly always soft, and do not scratch or 
harm the nose or lungs. When they are breathed into 
the body, they are caught on the moist surfaces of the 
nose and throat, and are driven out when the nose is 
blown. 

Dust which is hard and sharp is formed in many 
workshops. The dust which is produced by stone 
cutting and tool grinding contains sharp bits of stone or 
steel which injure the air tubes and lungs, and often 
lead to tuberculosis. There are two means of protect¬ 
ing workmen against harmful dust: (i) Hoods and 
suction pipes, which carry the dust away from the 
material on which the work is done, and prevent it 
from flying into the air. (2) Respirators worn by the 
workmen, which strain the dust from the air to be 
breathed. 

Dust which is poisonous may be produced in some 
trades, such as lead working. This dust may be kept 
out of the body by the use of suction pipes and res¬ 
pirators. It is also necessary that workmen wash their 
hands and faces before eating in order that none of the 
poisonous substances may reach their food. 

Disease Germs in Foul Air. — One of the greatest 
dangers from foul air is that of disease germs which 
may rise with dust. If a person has a cold, or tonsil¬ 
litis, or diphtheria, or other disease which is catching, 



FOUL AIR 


156 

he will expel disease germs with tiny drops of saliva 
and mucus from his nose and throat when he coughs, 
or talks, or sneezes, or blows his nose. The drops 
quickly dry, and their germs rise with the dust of the 
room and float in the air, and may then enter the 
bodies of other persons who breathe this air. Millions 
of germs fly off from every dried collection of mucus 
which is spit upon a floor or pavement. 

Wherever many persons meet, some one who has a 
cold or other infectious disease is likely to be in the 
room. For this reason the foul air of houses and meet¬ 
ing places nearly always contains disease germs. A com¬ 
mon way in which a cold, or a sore throat, or pneumo¬ 
nia, or tuberculosis is caught is by breathing air which 
has been made foul by some one who has the disease. 

Each pint of foul, dusty air of a crowded room or 
meeting place may contain fifty bacteria, and many of 
the bacteria are likely to be disease germs. Less than 
five bacteria may usually be found in a pint of outdoor 
air from a dusty city street, and if the streets are wet, 
the outdoor air will contain hardly any bacteria at all. 

It is almost impossible for you to catch a disease by 
breathing outdoor air unless the air is full of dust from 
a dirty street. If you keep a room supplied with 
clean outdoor air, you will not catch a cold or any other 
disease from the air, for there will be hardly any disease 
germs floating in it. 

Effect of Lights. — Lights which are produced by 
burning use up oxygen, warm the air, produce odors, 


FOUL AIR 


*57 


and make the air foul, just as breathing does. A candle 
uses about as much oxygen as a man. A bright light 
made by burning kerosene or gas uses about as much 
oxygen as five or ten men. Electric lights do not use 
oxygen or make the air foul, for their light comes from 
white-hot wires which lie inside of air-tight glass globes. 
Electric lights are usually the most healthful of all the 
means of lighting houses. 

How to Tell Foul Air. — The air of a room is consid¬ 
ered to be fresh, pure, and healthful when it is like 
the outdoor air on a mild, pleasant day. Three tests 
which any one can apply to air are those for odors, 
temperature, and dust. A fourth test is one for carbon 
dioxide, but that requires a laboratory equipment and 
a skilled observer. 

An unpleasant human odor in the air is one of the 
best signs that the air is foul. After breathing foul 
air for a few moments, you may become used to the 
smell, and may no longer notice it, but the air is then 
as unwholesome as ever. If you are not sure about 
the freshness of the air of your room, step out of doors 
for a moment. If you can notice an unpleasant odor 
when you come back into the room, the air is foul and 
unfit for breathing, and needs to be changed for fresh 
air from out of doors. 

A thermometer in a room will indicate the tempera¬ 
ture of the air. One can watch the temperature of 
the air of a room and regulate it by means of fires 
and windows. 


158 


FOUL AIR 


Dust in the air of a room can be seen and often 
smelled when it is abundant. 

Carbon Dioxide Test. — One may easily collect air 
to be examined for carbon dioxide by carrying a large 
glass bottle filled with pure water into a room, pour¬ 
ing out the water, and corking the bottle tightly. The 
air in the bottle is that from the room, and can be used 
for a laboratory test. 

When the amount of carbon dioxide in a room is 
doubled by breathing, the air begins to have an un¬ 
pleasant odor; and if there are many persons in the 
room, the temperature of the air begins to rise. When 
the amount of carbon dioxide is increased to ten or 
fifteen times its quantity in outdoor air, the air of the 
room has an offensively foul odor. 

Carbon Monoxide. — When a fire burns with a poor 
draft, it often gives off a half-burned gas, called carbon 
monox'ide. This is the gas which is often called coal 
gas. When a small amount of carbon monoxide is 
present in air which is breathed, it produces dizziness 
and headache. Larger amounts produce faintness, un¬ 
consciousness, and even death. It acts by uniting with 
the red blood cells and preventing them from carrying 
oxygen through the body. 

Carbon monoxide is one of the principal things in 
illuminating gas, and is often produced in stoves which 
burn coal, or charcoal, or kerosene oil. A gas stove, or 
oil stove, which is not connected with a chimney, may en¬ 
danger health by pouring carbon monoxide into the air. 



FOUL AIR 


159 


Carbon monoxide is also found in the exhaust gases 
of automobile engines, and has often poisoned those 
who were in a 
closed room in 
which an automo¬ 
bile engine was run¬ 
ning. The gas it¬ 
self has no odor, but 
other substances 
which are formed 
with it have un¬ 
pleasant odors, like 
those of illuminat¬ 
ing gas, which give 
warning of danger. 

If there is the least 
smell of gases in a 
room, the air is 
dangerous to health and possibly to life. 

QUESTIONS 

What is the composition of outdoor air? 

What changes are produced in air by breathing ? 

By what means is the composition of the outdoor air kept almost 
constantly the same ? 

What changes occur in the air of a living room or meeting place 
as the result of persons being in the room ? 

What effect does air which is made foul by breathing have upon a 
person ? 

How can you show that the air which comes from the lungs during 
quiet breathing will not support a fire ? 



A Source of Danger 

Keep the garage door open while the engine runs, 
so as to remove the carbon monoxide which is in 
the exhaust gases. 
















i6o 


FOUL AIR 


What is the difference between the breath of a person blowing a 
fire and the expired air of quiet breathing ? 

What are the four principal causes of the bad effects of ordinary 
foul air? 

At what temperature does the air of a room begin to feel close and 
warm ? 

How can you detect foul air by means of the sense of smell? 

What kinds of dust are unhealthful ? 

By what two methods may workmen be protected from unhealth¬ 
ful dust? 

When may you expect to find disease germs in the air? 

What are the effects of lights upon the purity of the air of a room ? 

What is the danger from an automobile engine which is running in 
a closed room ? 

For the Teacher. — Many experiments have been made to find out the 
causes of the bad effects of air which has been made foul by breathing. De¬ 
ficiency of oxygen and an increase in carbon dioxide were formerly believed 
to be the harmful conditions, but experiments prove that a person will not be 
affected by these conditions so long as the air contains enough oxygen to sup¬ 
port a fire. Perform the experiments with a burning candle in a jar. 

It will probably confuse the pupils to dwell too much on the various theories 
regarding the cause of the bad effects of ordinary foul air such as that in a 
close schoolroom. Four conditions which have definite effects are: 

1. Warmth. 

2. Odors. 

3. Dust. 

4. Disease germs. 

Warmth is the principal condition which produces discomfort, and bad 
odors are second. Emphasize the means of testing the purity of air by means 
of its odor. This is a reliable test, and may be applied quickly by any one. 

Demonstrate also the test of taking the temperature of the air by means 
of a thermometer. 

The carbon dioxide test is practicable only when a well-equipped laboratory 
is available. 

Dust is especially dangerous when it comes from stone or metal. Ordinary 
house dust is dangerous when it comes from an unclean room which is occupied 
by a careless person who has an infectious disease, for it may then contain 
disease germs. 

Emphasize the topic of carbon monoxide poisoning; the danger from the 
presence of this gas in the exhaust from automobile engines; and the need of 
ventilating a garage in which an automobile engine runs for only a moment. 


CHAPTER XIV 


VENTILATION 

Keeping Air Wholesome. — There are five methods 
of keeping the air of a room pure and wholesome: 

1. By changing the air often. 

2. By regulating the temperature of the air. 

3. By cleaning the room. 

4. By keeping the room in good repair. 

5. By admitting plenty of sunshine into the room. 
Ventilation. — Exchanging the impure air of a room 

for pure and fresh air is called ventila'tion. A small 
room will require a complete change of air within an 
hour if only one person is in it. A large room will 
require a complete change of air within a few minutes 
if many persons are in it. A schoolroom, church, or 
other meeting place needs to be ventilated all the time 
that it is in use, for the air will become unwholesome 
within a few minutes unless a stream of fresh air is 
constantly flowing into it. 

Reckoning How Much Fresh Air is Needed. — You 

can easily reckon how much fresh air a person needs. 
Suppose you were shut in an air-tight room which 
measures 10 feet square and 10 feet high. How long 

161 


OV. GEN. HYG. — II 


162 


VENTILATION 


could you stay in the room before the air would become 
foul? 

Air is foul when the amount of carbon dioxide is 
double that in outdoor air (p. 158). The room con¬ 
tains 10X10X10, or 1000 cubic feet. 

Since per cent, or 0.0004 of the outdoor air is 
carbon dioxide (p. 149), the amount of carbon dioxide 
in the room is 1000X0.0004 = 0.4 cubic foot = 691 
cubic inches. 

If another 691 cubic inches of carbon dioxide is 
added to the air, the air will be foul. 

Since there are 30 cubic inches of air in each breath 
of quiet breathing (p. 136), and 4 per cent of expired 
air is carbon dioxide, the amount of carbon dioxide in 
each breath is 30X0.04=1.2 cubic inches. 

Since 1.2 cubic inches of carbon dioxide is given off 
with each breath it will take yyy, or 576, breaths to 
produce 691 cubic inches of carbon dioxide and make 
the air foul. 

Since 20 breaths are taken each minute, it will take 
-^o 6 -, or 29, minutes to make 1000 cubic feet of air 
foul. 

This problem shows that a person makes 1000 
cubic feet of air foul each half hour. It also shows 
that each person in a room needs 2000 cubic feet of 
fresh air each hour in order to keep the air fresh and 
pure. 

How to Ventilate. — Some air will pass into and out 
of a room through cracks in its doors, windows, floor. 






VENTILATION 


163 

and walls. Well-built houses have few cracks, and 
only a little fresh air will enter them, unless openings 
are made to the outdoor air. 

One way of ventilating a room is to open a window. 
This is often the only way to get fresh air into a room. 



Diagram of the Natural Ventilation of a Room 
The arrows show the natural direction of the currents of air. 


It is easy to ventilate a room that is heated. Warm 
air is lighter than cold air, and will rise to the ceiling, 
like a cork on water. When the upper sash of a win¬ 
dow is lowered, a stream of foul air passes out above 
it. Fresh air enters the room between the two sashes, 






























































































164 


VENTILATION 


and through cracks in the other parts of the room. If 
foul air passes out of the room, we may be sure that 
other air enters the room. 

When the lower sash of a window is raised, foul air 
sometimes passes out through the opening, and some¬ 
times fresh air blows into the room through the open¬ 
ing, but whether the foul air blows out, or fresh air 
blows in, the air of the room becomes changed. 

Ventilators. — Many houses, schools, churches, and 
other meeting places have openings in the ceilings 
leading to attics, or to large pipes which open above the 
roofs like chimneys. These openings carry off the 
foul air, while fresh, cool air enters through the doors 
and windows. 

In large buildings, fans are often placed in the base¬ 
ments to force fresh air through the rooms. In this 
way the amount of air sent into the room may be reg¬ 
ulated, and the air of the room may be kept perfectly 
pure. 

Ventilating Bedrooms. — Some persons think that a 
bedroom does not need to be ventilated during the 
night if it is aired well during the daytime. A person 
sleeping in a small, closed bedroom will cause the 
roomful of fresh air to become foul within an hour 
after he goes to bed. He will then breathe foul air 
through all the rest of the night, unless he ventilates 
the room. 

Many suppose that a person will not be harmed by 
breathing air which he himself has made foul. Im- 



VENTILATION 165 

pure air is as poisonous to the person who makes it 
foul as it is to another person who may breathe it. 

Sleep with your bedroom window open all night 
long. If the air is cold, use plenty of bedclothes, and 
you will sleep comfortably and healthfully, and awake 
refreshed. 

Sleeping on an outdoor porch will induce rest and 
promote health and strength. Outdoor sleeping is 
one of the best means of restoring health to those who 
have tuberculosis. 

The Arithmetic of Ventilation. — If twenty persons 
are in a room, how wide should the windows be opened 
in order to keep the air of the room fresh? 

The quantity of fresh air which should enter the 
room each hour is at least 40,000 cubic feet, whether 
the room is large or small, for each person needs 2000 
cubic feet of fresh air each hour. 

A gentle current of air that barely shakes a curtain 
will move about four feet a second, or about as fast as 
a man walking rather slowly. If air flows at that 
rate through a window three feet wide, which is opened 
four inches, four cubic feet will pass through the 
opening in one second, 240 cubic feet in a minute, and 
14,400 cubic feet in an hour. Therefore, three win¬ 
dows will have to be kept open four inches in order to 
supply the 40,000 cubic feet of air per hour which 
twenty persons need. If the air currents move rapidly 
enough to make a cold draft across the room, or to 
blow the curtain aside, smaller openings may supply a 



i66 


VENTILATION 


sufficient quantity of fresh air. If the outdoor air is 
warm and still, larger openings will be required. 

Drafts. — Many persons do not ventilate their 
rooms and meeting places during cold weather because 
they fear that drafts will produce the forms of sickness 
called colds. A cold is caused by disease germs which 
come from other sick persons, just as measles comes 
from germs which another person gives off from his 
body. If a person gives off the germs of a cold to the 
air of a room, any one who breathes the air may take 
the germs into his nose and throat, whether there is a 
draft in the room or not. The time to open a window 
and begin to ventilate is as soon as any one comes 
into a room, and before the air becomes foul. If the 
air of a room is pure and fresh, there will be no disease 
germs in it and a person will not catch a cold from 
breathing the air. 

It is nearly always possible to ventilate a room with¬ 
out producing drafts. One way is to drop the upper 
sashes of the windows on the side of the room which is 
opposite to that on which the wind blows. The main 
stream of air will then flow out of the room, and fresh 
air will enter in many small streams through cracks in 
the doors and windows. 

Another way is to tack a sheet of thin muslin to a 
frame, and place it in an open window as you would 
a mosquito screen. This will allow fresh air to enter 
the room, but will prevent it from blowing across the 
room" in a draft. 



VENTILATION 


167 


Ventilation for Coolness. — Attention to the tem¬ 
perature of a room is necessary in order to keep its 
air comfortable. A common fault in winter is that of 
heating the air of a room as warm as the outdoor air 
on a hot day in summer. It is often necessary to 
open the windows of a meeting hall or schoolroom in 
order to keep the air comfortably cool. 

Bacteria in Dust. — One of the principal reasons 
why foul air is dangerous is that persons who breathe 
the air stir up dust and disease germs from the floors, 
carpets, and furniture. If a room is clean, only a little 
dust and very few bacteria will rise into the air. Keep¬ 
ing a room well swept and dusted will prevent a great 
deal of sickness. 

Sweeping and Dusting. — While you are sweeping 
a room, open its outside doors and windows so that 
the dust will be blown away. When you dust the 
furniture use a moist cloth; this will hold the dust 
and prevent its being scattered through the air again. 

Sweeping will not remove all the dirt from carpets 
which are tacked down to the floor, for a broom will 
remove only the dirt which is on the surface, and will 
not take out the dirt and dust which lie among the 
threads, or under them. Rugs are more healthful 
than carpets, for they may be taken up and cleaned. 

A vacuum cleaner is an excellent thing for cleaning 
carpets and cushions, for the dirt and dust are forced 
up from among the threads, and held in a tight box 
from which they cannot escape into the air. 


i68 


VENTILATION 


State of Repair of Floors. — Dirt collects on a rough 
floor and in cracks between the boards, and dust rises 
from the floor when any one walks across the room. 
Keeping the floor of a room in good repair is necessary 
in order to prevent dust and the unpleasant odors of 
dirt in the air of a room. 

A floor which is varnished or painted is hard and 
smooth, and dust and dirt may be easily removed from 
it. The floors of schoolrooms and other meeting places 
are likely to be worn and soiled by the feet of many 
persons walking across them. Oil is an excellent thing 
for these floors, as it will help to harden the floors and 
will prevent the rise of dust from them. 

Sunshine in a Room. — Disease germs will often 
stay alive for days and weeks in dark, damp corners of 
rooms and closets, but sunlight will dry a room, and 
will also kill the disease germs which may be in it. 
Sunlight, cleanliness, and fresh air are the best of all 
means for making a room healthful. 

Many old houses have rooms which do not have a 
single window opening into the outside air. These 
rooms are breeding places of disease, for they receive 
neither light nor fresh air. Most cities now have laws 
that every room in a house shall have windows opening 
into the outside air. There are also laws that large 
air shafts shall be left open between crowded buildings, 
so that every room may get air and light. But edu¬ 
cation is needed in order to impel the people to make 
use of the air and light. 



VENTILATION 


169 


QUESTIONS 

What is ventilation ? 

How much fresh air does each person need in an hour? 

How can you ventilate a room? 

How does heating a room help to ventilate it ? 

When should you begin to ventilate a room in which a crowd 
gathers? 

How rapidly may a current of air move through a window with¬ 
out making a strong draft? 

How can you reckon how wide to open the windows of a room in 
order to ventilate it properly? 

How can you prevent a draft in a room while ventilating it ? 

Why should you keep a window of your bedroom open all night ? 

How should you sweep and dust a room? 

Why is a vacuum cleaner an excellent machine to use for cleaning 
a room? 

How do painting and repairing a floor help to make a room 
healthful ? 

Why are rugs more healthful than carpets? 

How does sunshine help to make a room healthful? 

Why do cities have laws regulating the number of windows in a 
room? 

For the Teacher. — Coordinate this lesson with arithmetic. Reckon the 
amount of fresh air which a person needs each hour. Also reckon the inflow 
of fresh, cool air through a window. 

Demonstrate methods of ventilation by means of windows. Test the direc¬ 
tion and force of the flow of air in ventilation by holding a lighted candle near an 
open window, and in various other parts of the schoolroom. Emphasize the 
benefit of keeping the windows of a bedroom open at night. 

Discuss drafts, — the unwise fear of them, and methods of preventing them. 

Demonstrate methods of sweeping and dusting by which dust is not 
scattered through the room. 

The peppery, pungent odor in the air of closed, unoccupied rooms is usually 
caused by molds growing on the floors and carpets. 


CHAPTER XV 


BODY HEAT 

Source of Body Heat. — The body is nearly always 
warmer than the air around it. Its heat is produced 
by the oxidation, or slow burning, of its food and flesh 
(p. 133). When food and flesh are oxidized in the body, 
they yield the same amount of heat that they would 
produce if they were burned outside of the body. 

The oxidation takes place more rapidly in some 
parts of the body than in others. It is rapid in the 
liver and in the muscles while they are at work ; and it is 
very slow in the bones and skin, and in the hands and 
feet. But the blood takes the heat from the liver and 
muscles and carries it to the skin, the hands, the feet, 
and all the rest of the body ; and so it keeps all parts of 
the body at nearly the same warmth. The body is 
warmed by the blood in the same way that a house is 
heated by a hot-water system. The blood is like the 
hot water which carries heat from the furnace ^to 
the radiators in the rooms. When your hands are cold, 
you can warm them by making the blood flow through 
them rapidly, as by clapping them together or whip¬ 
ping them around your back. 


BODY HEAT 


I 7 I 

Measuring Heat. — The heat of the body is measured 
in two ways: 

1. Its hotness in degrees of temperature. 

2. Its quantity in calories. 

The difference between temperature and amount of 
heat may be illustrated by a match and a pailful of 
warm water. A burning match has a high degree of 
temperature, but the pail of warm water contains 
a thousand times more heat than the match. 



Two Thermometers Used for Taking the Temperature of 

the Body 

The upper one is shown as indicating the natural temperature of the healthy 

human body. 

Thermometer. — Degrees of temperature are meas¬ 
ured by means of a thermometer. When a doctor ex¬ 
amines you, he usually takes your temperature by plac¬ 
ing a thermometer under your tongue for a minute or 
two. If you are in good health, your temperature is 
about 98-^ degrees on a Fahrenheit thermometer, and 
we write it 98.5° F. If your temperature is less than 
98° F., you are cold or chilly. If it is ioo° F., or 
more, you have a fever and are sick. A temperature 
of 104° F. is a high fever and a sign of severe sickness. 



172 


BODY HEAT 


A fever is usually caused by disease germs growing in 
the body. 

Calories. — If heat is put into an object, that object 
becomes warmer and its temperature rises. A calorie 
(sometimes called “large calorie”) is the amount of 
heat which will raise the temperature of one kilogram 
of water one degree Centigrade, or one pint of water 
about four degrees Fahrenheit. It takes about fifty 
calories to heat a pint of ice-cold water boiling hot. 
One can measure the amount of heat which a substance 
can produce by burning a small amount in a cup that 
is surrounded by water, and seeing how many degrees 
it warms the water. An ounce of sugar or of protein 
will produce 120 calories, and an ounce of fat, 240 
calories. 

The body of a grown person doing light work needs 
about 2400 calories in a day in order to keep its tem¬ 
perature at 98.5° F. The oxidation of food in the 
body produces heat about as fast as two burning 
candles. An ordinary candle weighs about one ounce. 
It will burn about 4 hours and will produce about 240 
calories of heat. It will take 6 candles lighted one 
after another to keep burning 24 hours, and they will 
produce 6 times 240, or 1440 calories. Twelve candles, 
enough to keep burning two at a time 24 hours, will 
produce 2880 calories, which is only a little more than 
the amount of heat that a grown person usually needs in 
a day. You will need to know about calories in order 
to study foods, because one of the principal ways to 


BODY HEAT 


173 


judge the value of a food is by the number of calories 
which it will yield to the body. The value of coal 
or other fuel is also judged by the number of calories 
which it will produce when it is burned. 

Regulation of Body Temperature. —Your body does 
not produce the same amount of heat at all times. It 
produces much heat while you are running, and only a 
little while you are sitting still; and yet if you are 
healthy, the temperature of your body remains 98.5° F. 
You may feel too warm while you run, but your body is 
then no warmer than it is while you sit still and are com¬ 
fortably cool. 

The body regulates its temperature in two ways: 

1. By the touch of the cool air around it. 

2. By the perspiration. 

Cold Air. — The body is always losing heat to the air 
which touches it, if the air is cooler than the body. If 
the air is cold, it cools the body rapidly, but if it is warm, 
it cools the body slowly, or not at all. The skin is like 
the radiator of an automobile, and the blood is like the 
water which flows through the radiator. When the air 
is cold, or when one sits still and produces only a small 
amount of heat, the blood tubes of the skin contract, 
the skin becomes pale, only a small quantity of blood 
flows near the cold air, and so the body saves its heat. 
But when the air is warm, or much heat is formed, the 
blood tubes of the skin expand, the skin becomes red, 
and a great deal of blood flows near the air in order that 
the heat may pass off rapidly. 



174 


BODY HEAT 


Some animals lose their heat almost as fast as they 
produce it. The temperature of fishes, frogs, snakes, 
and insects is nearly the same as that of the air or water 
in which they live. These animals are cold-blooded. 
They are active while the air or water is warm, but are 
sluggish and almost lifeless when the air or water is cold. 

Cold-blooded land animals, and some warm-blooded 
animals, such as woodchucks, lie under the soil or in the 
mud all through cold weather, and appear almost lifeless 
until the warm spring weather. The long winter’s sleep 
of these animals is called hibernation. 

Whales and seals are warm-blooded animals which 
live in the water. Although the water may be almost 
freezing cold, yet the temperature of these animals is as 
high as that of man, because a thick layer of fat under 
their skins prevents the heat of their bodies from passing 
off to the water. 

Cooling by Perspiration. — When the air is very 
warm or hot, it does not cool the body by its touch, and 
yet the temperature of a healthy body does not rise, be¬ 
cause the perspiration cools it. A teakettle will illus¬ 
trate the way in which perspiration cools the body. 
When a kettle of cold water is placed over a fire, the 
temperature of the water rises until it reaches 212° F., 
and the water begins to boil. The temperature of the 
water then remains at 2i2°F., because the steam carries 
away all the heat that goes into the water. 

When you perspire, the water of the perspiration be¬ 
comes a vapor and carries away the heat that would 


BODY HEAT 


175 


warm the body above 98.5° F. Some perspiration is al¬ 
ways passing off and cooling the body, even on a cold 
day of winter. Touch your dry finger to a cold glass. A 
spot of vapor on the glass will show that perspiration is 
passing off from your skin. When the day is hot, a great 
deal of perspiration is formed in order to cool your body. 

The perspiration is the principal means of cooling the 
body on a hot day. You are in no danger from heat as 
long as you perspire freely; but when you lose a great 
deal of water and can no longer perspire, the tempera¬ 
ture of your body quickly rises, you have a fever, and are 
weak and faint. This sickness is called a sunstroke , or 
a, heat stroke. You need to drink much water on a hot 
day so that you will perspire freely and keep your body 
cool. Water that is somewhat cool will cool your body 
as well as ice water, for it is the perspiration, and not the 
coldness of the water, which cools you. 

Humidity. — Air contains vapor of water. When 
the air contains only a little water, it takes water from 
wet objects, and so it makes them dry. When air con¬ 
tains all the water it can hold, as on a foggy day, wet 
objects do not become dry, because the air cannot take 
up their water. The wetness or dryness of the air is 
called its humid'ity. 

If there is a great deal of water in the air, it affects 
the body in three different ways, which vary with the 
temperature: 

1. This moisture is uncomfortable and harmful to 
the body when the air is very warm. 


176 


BODY HEAT 


2. It often adds to the comfort of the body when the 
air is just comfortably warm. 

3. It feels uncomfortable and chilly when the air is 
cold. 

If the air is hot and full of water vapor, the perspira¬ 
tion does not dry from the skin, the body is not cooled, 
and its temperature may rise until there is a fever. If 
the air is dry, perspiration dries from the skin rapidly 
and cools the body even when the air is hot. A person 
can stay in a hot oven safely so long as he perspires 
freely. 

You suffer from the heat greatly on a warm, humid 
day in summer. You suffer in the same way from the 
heat in winter when your living rooms and meeting 
places are poorly ventilated, because the air of heated, 
unventilated rooms is often as hot and moist as out¬ 
door air on a hot summer’s day. Many of the bad 
effects of impure air are caused by the heat and mois¬ 
ture of the air, and these may be prevented by venti¬ 
lation (p. 152). If the windows of a heated room on a 
cold day are wet with vapor which comes from the air, 
the air is usually too hot and moist for comfort and 
health, and the room is in need of ventilation. 

The most comfortable temperature of the air of a 
living room is about 70° F. (p. 153). If the air at that 
temperature is very dry, it takes up perspiration rapidly, 
and is likely to make the body feel cold. But if the air 
is moist, it does not takeaway the perspiration, the body 
loses little heat, and one feels warm. Moist air at a 


BODY HEAT 


177 


temperature of 65° F. feels as warm as dry air at 70° F. 
When you heat a room in winter, you can save heat by 
making the air moist. Place a pan of water on the stove 
or radiator so that its vapor will pass into the air. If 
you have a hot-air heater, keep its water box filled. 

Cold air which is damp and foggy takes heat from 
the body more rapidly than that which is dry. A 
damp wind that is just above freezing makes you feel 
colder than a dry wind which is much colder than freez¬ 
ing. You judge the coldness of the air by its dampness 
as well as by its temperature. If the day is damp and 
foggy you need to wear more clothes than when the air 
is dry. 

Taking Cold. — It used to be supposed that coldness 
was the cause of the kinds of sickness which are called 
colds. It is now known that colds are caused by disease 
germs which come from other people, and from foul air 
and dust. Air which is cold and damp has no more dis¬ 
ease germs than air which is warm and dry. On cold 
or damp days, people keep their doors and windows 
closed, and the air of their houses becomes foul and full 
of disease germs. They then catch cold by breathing 
the foul air when they go into the house to warm and dry 
themselves. Coldness and chills do not make a person 
take cold unless he takes living germs of the sickness 
into his body. 

There is a way by which coldness and dampness may 
help a person to catch cold when he takes disease germs 
into his body. Cold air blowing upon the body may 


OV. GEN. HYG -12 



178 


BODY HEAT 


weaken it so much that the white blood cells cannot 
destroy disease germs when they enter the body (p. 96). 
If the body is chilled, the white blood cells may not be 
able to destroy the disease germs which they are usually 
able to overcome. But there must be disease germs in 
the body before a cold can develop. Remember also 
that disease germs in the body may cause a cold 
whether the body has been chilled or not. 

Weather. — Some persons think that during bad 
weather the outdoor air contains something which is 
likely to make them sick, and so they shut the air out of 
houses on unpleasant days. Most diseases which are 
supposed to be due to bad weather are caused by disease 
germs in the foul air of houses and meeting places, and 
not by the outdoor air. 

Weather and climate consist principally of four 
conditions of the outdoor air: 

1. Temperature. 

2. Motion, or the wind. 

3. Dampness, such as rain or fog. 

4. Sunshine. 

The principal direct effect which weather has on 
health is that it produces changes in the temperature 
of the body. But man can easily protect himself 
against unpleasant weather by means of houses and 
clothes. 

Voluntary Regulation of Temperature. — There are 
four principal ways by which one can help to keep the 
body comfortably warm: 




BODY HEAT 


179 


x. By heating houses and living rooms. 

2. By clothes. 

3 - By exercise. 

4. By food. 

Heating Houses. — When the temperature of the 
outdoor air is below 6o° F., living rooms usually need 
to be heated. Some persons close their heated rooms 
tightly in order to save heat, and when they do so the 
air soon becomes foul. It would be easy to heat a house 
if it were not for ventilation. 

There are five principal means of heating houses, 
namely : fireplaces ; stoves; gas or oil heaters ; a hot¬ 
air furnace; and steam or hot-water radiators. 

The principal difference in the healthfulness of these 
five means of heating is in their effects on ventilation. 
A fireplace causes a strong draft of air to rise up the 
chimney, and so it ventilates a room. A stove does 
not ventilate a room nearly so much as a fireplace 
does. 

A heater which burns gas or oil pours its waste prod¬ 
ucts into the air and makes the air foul, unless it is con¬ 
nected with a chimney. Electric heaters are healthful, 
for no burning takes place in them and they do not make 
the air foul. 

A hot-air heater warms a house by means of a stream 
of air which passes over the hot furnace and into the 
rooms. It ventilates a room while it heats it. The air 
will usually be too dry unless the air is kept moist 
(p. 176). Rooms that are heated by steam or hot 


i8o 


BODY HEAT 


water need to be ventilated because the radiators do 
not bring fresh air into the house. 

Clothing. — Clothes keep the body warm because 
they prevent heat from leaving the body. They do not 
make heat, but they help to hold that which is produced 
by oxidation. They hold the heat by two means : 

1. The cloth itself. 

2. The air which is held in the fibers and layers of 
the clothes. 

The air in clothes is almost as important as the cloth 
of which clothes are made. Clothes which fit tightly are 
cold, because the air is crushed out from among the 
fibers. Clothes which fit loosely are warmer than 
tight ones; two or three thin garments, than one thick 
one; and cloth loosely woven, than that which is firm 
and hard. 

Wear enough clothes to keep you warm. Prepare 
for cold weather and storms so that you can keep all 
parts of your body both warm and dry. 

Wet Clothing. — If clothes are wet, the heat of the 
body causes the water to dry from them, and the vapor 
takes away heat and makes the body feel cold. Damp 
clothes are harmful when they cool the body. They 
will not usually harm the body during exercise, for the 
exercise will keep the body warm. They are harmful 
when a person sits still, for they may then cool the body 
more rapidly than the body can replace the heat. 

Exercise. — When the muscles are exercised, food or 
flesh is oxidized, and heat is produced. One fourth of 




BODY HEAT 


181 


the heat is turned to power which gives the body 
strength to work. Three fourths of the heat goes to 
warm the body, and does not add to the strength or 
power to work. Exercise makes the body warm. Al- 



WARMING THE BODY BY EXERCISE 

When you take exercise, one fourth of the heat of oxidation is used up 
as power, and three fourths goes to warm the body. 


most the only way to increase the amount of heat which 
the body produces is to take exercise. A person can 
easily keep warm in the coldest weather by exercising. 

When the body is cold, its muscles contract, and 
tremble or shiver. The contraction of the muscles pro¬ 
duces heat, and so shivering helps to warm the body. 

Cold muscles cannot act well, and cold nerves cannot 
feel. When your hand is cold, it has no strength and 




182 


BODY HEAT 


is numb. If you whip your cold hands together, or 
around your shoulders, you send warm blood through 
them and restore their warmth, strength, and feeling. 

Food. — When the weather is cold, you need plenty 
of food in order to carry on oxidation and produce heat 
enough to keep the body warm. One reason why the 
Eskimos can live in the cold north is that their most 
abundant food is fat meat, which produces a great 
deal of heat. A wild bird or animal can endure severe 
cold if it has plenty of food to keep up the oxidation in 
its body. You will not mind the cold if you have plenty 
of food, and exercise hard in the cold air out of doors. 

QUESTIONS 

What produces the heat of the body ? 

Compare the method of heating the body with a hot-water system 
of heating a house. 

What is the natural temperature of the body? 

What is a fever? What is usually its cause? 

What is a calorie? 

How many calories does the body need to produce in a day? 

In what two principal ways does the body regulate its temperature? 

How does the perspiration cool the body? 

What is the cause of a heat stroke? 

What is the meaning of the word humidity? 

Why does moisture in the air increase the feeling of warmth on a 
warm day, and of coldness on a cold day? 

What is the most comfortable temperature for the air of a room ? 

Why does moist air at a temperature of 65° F. feel as warm as dry 
air at a temperature of 70° F. ? 

What has cold weather to do with one’s catching a cold? 

What conditions of the air make up the weather? 


BODY HEAT 183 

Compare the healthfulness of the various methods of heating 
houses. 

How does clothing keep the body warm ? 

What has the air in clothing to do with keeping the body warm? 
How does exercise help to warm the body ? 

How does food help to warm the body? 

For the Teacher. — Animal heat is popularly supposed to be a mysterious 
thing, and changes in the temperature of the body are blamed for infectious 
diseases and all manner of pains and aches. In this chapter the ordinary laws 
of physics are applied to the subject of body heat. 

Emphasize the topics of the source of the heat of the body, and its measure¬ 
ment in degrees of temperature and in calories. Develop the concept of a 
calorie in some detail, for it is at the basis of a common method of judging the 
value of foods. The calorie (or large calorie) used in measuring food values is 
1000 times as great as the calorie, or small calorie, used in physics. 

Teach the various degrees of temperature which are often mentioned in 
hygiene, such as the freezing point, the boiling point, the temperature of a 
healthy person, a fever temperature, and the most comfortable temperature 
of a room. 

Explain the two methods by which the human body automatically regu¬ 
lates its temperature; and show how man augments these methods by heating 
houses, by clothes, by changing the humidity of the air of houses, by exercise, 
and by food. 

Dwell upon the four elemental conditions which go to make up what is 
called weather and climate ; and show how the weather of a room on a winter’s 
day may be as hot, humid, and uncomfortable as the outdoor air on a hot, 
moist day of August. 

Emphasize this truth, that the essential factor in taking cold and catching 
diseases is the taking of disease germs into the body; and that cold, heat, 
dampness and other conditions of the air, soil, and weather are causes which 
are less important than infection. 


CHAPTER XVI 


THE SKIN 

The body is wrapped in a soft skin which is as thick 
and strong as that of a dog or a calf. Pinch your skin 
in several places and lift it up, and notice three things 
about it: 

1. It is loosely attached to the flesh beneath it. 

2. It stretches easily, but is elastic and springs back 
into place when you release it. 

3. On the back of the hand it is as thin as a kid glove ; 
on the arm and face it is as thick as shoe leather ; and on 
the back of the neck it is as thick as sole leather. 

The skin consists of two layers: 

1. A very thin outer sheet called the epidermis 
(ep-i-dur'mis). 

2. The thick main part called the dermis , or true 
skin. 

Epidermis. — The word epidermis means upon the 
skin. The epidermis is like a sheet of thin paper pasted 
upon the true skin. It is as thin as tissue paper or card¬ 
board over most of the body, but is as thick as wrapping 
paper on the palms and soles. It is the part which is 
raised when a blister forms on the skin, and which peels 
off when the skin heals after a sunburn. Take a fine 


184 


THE SKIN 185 

needle and thrust it under the skin as near the surface 
as possible. You can easily raise the epidermis in a 
loop without causing pain or bleeding, for it has no 
blood tubes or nerves. 

The epidermis is composed of epithelial cells, 
matted together to form a sheet (p. 27). Wet a 
spot upon your skin 
and rub it hard until 
it is.dry. You can rub 
loose cells from the sur¬ 
face, and form them 
into rolls. These are 
cells of the epidermis. 

You shed about a table¬ 
spoonful of cells from 
the epidermis every day, 
and can see them on 
your skin and clothes 
when you do not re¬ 
move them by bathing. 

The whole epidermis is 
shed and a new one is 
formed about once a 
month. 

The epidermis protects the true skin and the flesh 
beneath it. A spot of skin from which it is removed is 
tender and sore, but it grows thick and forms a hard 
covering, called a cal'lus , upon a spot which is rubbed 
hard. If you work hard with your hands, you may in- 



Section of the Skin 
(Magnified ioo times.) 


Epidermis 


True skin 


Sweat gland 


_ Fat 





i86 


THE SKIN 


jure the growing epidermis at first and produce a blister; 
but after a few days of work, spots of callus will grow in 
order to protect the flesh from harm. 

A tight shoe pressing on your foot may cause the 
epidermis to form a small callus, called a corn, which is 
tender and painful. You can prevent corns from form¬ 
ing by wearing shoes which fit the feet snugly without 
cramping them. 

The epidermis is waterproof, and forms a covering 
which is like a sheet of rubber upon the skin. Very 
few substances which we usually handle can pass 
through it to enter the flesh. Poisons and disease germs 
may be handled with safety because they cannot pass 
through a healthy skin. But any wound or sore upon 
the skin is dangerous because disease may pass through 
it into the flesh, if it is not protected and dressed 
(p. 123). When a mosquito sucks blood, it thrusts its 
bill through the epidermis into a blood tube in the true 
skin. Some kinds of mosquitoes may carry the germs 
of malaria in their bodies and inject them into the 
flesh when they suck blood, and so they cause the 
bitten person to have malaria (p. 45). / 

Most liniments and other medicines which are placed 
upon the skin do not enter the body, for they cannot 
pass through the epidermis. The good which they do 
comes from the rubbing with which they are applied to 
the flesh. But a medicine may be given through the 
skin by means of a hypoder'mic syringe and a hollow 
needle thrust through the epidermis into the flesh. 


THE SKIN 


187 


Substances from within the body cannot pass through 
a healthy epidermis, but when the epidermis is 
wounded, the injured spot becomes wet with lymph 
which oozes from the flesh. When the skin is scalded, 
the young, growing cells of epidermis are injured, and 
the lymph oozes through them and lifts up the outer 
layer of epidermis and forms a blister. 

Lymph, oozing from a small wound, may dry upon 
the surface and form a hard covering, called a scab , 
which protects the raw flesh. A scab is nature’s dress¬ 
ing for a wound. It is an excellent dressing when the 
wound is clean and has no disease germs in it. 

When a wound or a sore heals, new epidermis grows 
at the edge of the sore and spreads over the raw place, 
like grass over a bare spot of lawn. At the same time 
new flesh forms upon the sore spot and continues to 
grow until the epidermis covers it. If the epidermis 
does not grow rapidly, the flesh may grow up and form a 
soft mass called proud flesh. When a doctor treats a 
sore, he tries to make the epidermis grow as fast as pos¬ 
sible. The epidermis stops the growth of flesh and 
completes the healing. 

It will take the epidermis a long time to cover a raw 
spot when the sore is large. The healing may be has¬ 
tened by skin grafting, which is done by cutting some 
growing epidermis from healthy skin and placing it on 
the sore. It will grow and form a new covering of epi¬ 
dermis. Skin grafts may be taken from another person, 
or from a lower animal, such as a frog. 


i88 


THE SKIN 


The color of the skin is caused by two things: 

1. The red blood in the skin showing through the 
epidermis, which is almost transparent, makes the skin 
pink. When you are faint, there is little blood in your 
skin and you are pale. 

2. A layer of cells in the deep part of the epidermis 
contains a brown substance. Colored persons have a 
great deal of the coloring matter in their epidermis; 
blond people have little ; albinos (al-bl'noz) have none ; 
and freckled persons have it in spots. 

When the sun shines on the skin for some time, the 
cells take up more coloring matter and cause the skin to 
become brown, or tanned. The coloring matter is like 
a dark curtain which protects the skin from becoming 
sunburned. Blond persons do not form the coloring 
matter readily, and so they become sunburned more 
easily than those with dark skins. 

The True Skin. — The dermis, or true skin, is like an 
animal’s hide. It is composed of tough connective 
tissue fibers which are as strong as those in the skin of 
an animal. Leather is the dermis of a lower animal 
hardened by soaking in a tanning fluid. 

The dermis contains three structures which have im¬ 
portant uses in the body ; namely, blood tubes, nerves, 
and glands. 

Blood Tubes.—The skin contains many blood 
tubes. One of the principal uses of the blood tubes is 
to regulate the temperature of the body (p. 173). 
The tubes expand when the body is becoming too 



THE SKIN 189 

warm, and they contract with the cold. Heat makes 
the skin red, and cold makes it pale. 

Your feelings also affect the blood tubes of your skin. 
They expand and become full of blood when you blush, 
or are angry or excited. They contract and make you 
pale when you are frightened. 

Nerves. — The skin contains more nerves of feeling 
than almost any other part of the body. They are most 
abundant in the tips of the fingers, and so we use the 
finger tips in feeling of objects. 

The nerves of the skin end in peaked ridges, called 
papil'lae , which project into the epidermis. The pa¬ 
pillae are numerous and large on the palms of the hands 



Finger Prints 

The surface of the skin of the palms and soles has raised lines which 
will print like type when they are inked. 


and soles of the feet, and there they form lines in circles 
and spirals. Press your finger upon the ink of a stamp¬ 
ing pad, and then upon a piece of white paper. The 
lines of your skin will form their print upon the paper. 
No two persons have the same pattern of finger prints, 






THE SKIN 


190 

and so a person may be recognized by means of his finger 
prints. Every soldier in the American army during 
the World War had his finger prints taken, for that was 
the surest way by which he could be recognized if he 
were killed. 

Glands. — Glands in the skin form two useful sub¬ 
stances ; namely, perspiration, and an oil. 

Perspiratory Glands. — A perspir'atory gland con¬ 
sists of a tube running from the surface down deep 
into the true skin. The tube is lined with plump cells 
which fill it so full that only a narrow space is left in 
its center. The cells are like those in the epidermis. 
The gland looks as if a pin had been thrust into the 
flesh and had carried with it a covering of epidermis 
which had clung to it. 

Perspiration is made by the cells of the gland out of 
material which is brought to them by the blood. It 
flows out of the tubes and upon the surface of the 
skin. The pores of the skin are the openings of the 
perspiratory glands. Nothing enters the pores, and 
nothing except perspiration leaves them. 

Oil Glands. — Special glands of the skin produce an 
oil which keeps the epidermis soft and smooth. The 
oil glands are like those which produce perspiration, 
except that they are short and branched, and they 
usually open beside a hair root. 

The skins of many persons break out with fine red 
spots, called prickly heat , because, when they bathe, 
they use a soap which injures the epidermis. Taste the 




THE SKIN 


191 


soap which you use. If it burns your tongue, it 
will be likely to harm your skin by taking away its 
oil. A mild soap, like castile, is helpful to the skin, 
for it dissolves the dirt and loose oil without harming 
the epidermis. 


D 


C. 

B 

A 


A Hair and the Parts Connected with It 

(Magnified 100 times.) A, hair root extending nearly all the 
way through the skin; B, a muscle which pulls the root upright; 

C, glands secreting an oil which softens the hair; D, epidermis. 

Hair. — Hairs grow over almost the whole body ex¬ 
cept the palms of the hands and soles of the feet. You 
can easily find them, even on a baby, if you look sharp. 

A hair is formed out of epidermis cells which lie in the 
bottom of a deep tube. As the cells grow, they become 
molded into a solid hair. A curly hair is fiat like a rib¬ 
bon, but a straight hair is round like a string. An oil 









192 


THE SKIN 


gland is connected with each hair in order to soften it 
and the skin. A slender band of involuntary muscles 
is also connected with each hair root. When your skin 
is cold, the muscles contract and lift the hair roots and 
cause a roughness of the skin, called goose flesh. 

The only part of a hair which is alive is its lower part 
where the cells are soft. If a hair is pulled out, the soft 
growing cells at its root are left, and soon form a new 
one. A hair root lies too deep to be reached by medi¬ 
cines or liniments rubbed on the surface. You can keep 
your hair in good order by combing and brushing it, and 
by washing it and the scalp as you would the rest of 
your body. 

Nails. — A nail is formed at its hinder part out of 
epidermis cells which grow under the flesh. As new 
cells grow, they push the whole nail forward. 

The dirt which collects under the outer ends of the 
nails may contain disease germs. Keep your nails 
neatly trimmed even with the ends of your fingers. 
Clean the dirt from under their ends. 

A hangnail is a sliver of epidermis which has been 
torn from the skin just behind the nail. Do not tear or 
bite it off, but cut it off close to the skin. 

Complexion. — The appearance of the skin is called 
the complexion , and depends on three principal causes: 

1. Blood. 

2. The waste matters in the body. 

3. The smoothness and clearness of the epidermis. 

The skin shows a great deal about the state of the 



THE SKIN 


193 


health. A healthy person will nearly always have a 
good complexion. Plenty of good red blood flowing 
through the body gives the skin a pink color which is a 
sign of good health (p. 188). Waste matters, such as 
bile, circulating with the blood, stain the skin and 
give it a brown or yellow color. Pimples, sores, and 
scaly spots on the skin are usually signs that the body 
is in ill health. 

There are two principal ways by which one may im¬ 
prove the complexion : 

1. By treating the skin itself. 

2. By caring for the health of the whole body. 

It is important that you should keep your skin clean by 
washing and bathing it. You can help your skin by re¬ 
moving its dirt and waste matters ; but you can seldom 
improve your complexion by rubbing things on the skin. 
Medicines, paints, and powders give the skin a make- 
believe look. When you use powder and paint on your 
skin, everybody can see that you have only an imitation 
complexion. x\lmost the only thing which you may need 
to rub on the skin is a little oil or cold cream to soften 
it when it is too dry or soothe it when it is irritated. 

You can do a great deal for the skin by treating it 
from the inside of the body. Almost the only way by 
which you can improve the complexion is by improving 
the health of the whole body. If your body is healthy, 
your skin will take care of itself, and will be clear and 
soft and beautiful, like the skin and fur of a wild animal 
that is fat and sleek. The skin and complexion are 


OV. GEN. HYG.-13 


194 


THE SKIN 


helped by such means as careful eating, exercise, fresh 
air, sunshine, work, play, and rest; and by getting rid of 
the waste matters of the body. Anything which helps 
to make you strong and healthy will help your skin and 
complexion. 

Bathing. — The skin often becomes soiled and needs 
to be cleansed by bathing. Dirt on the skin consists of 
four principal substances: 

1. Perspiration. 

2. Dead epidermis. 

3. Disease germs. 

4. Dirt which comes from the soil, the air, and sub¬ 
stances which touch the body. 

Perspiration and dead cells of the epidermis decay and 
produce unpleasant odors. Germs of disease may cling 
to the hands and other parts of the body, and some 
kinds may grow among the dead cells of the epidermis. 
The body must be bathed for the sake of health as well 
as good looks. 

You may know that your body needs a bath when 
you can see the dirt or when the skin has an unpleas¬ 
ant odor. 

Your body is always giving off perspiration and shed¬ 
ding dead epidermis. You need a bath even when you 
do not touch dirty things. Bathe the whole body in hot 
soapsuds at least once a week, and more often than that 
if the air is dusty, or if you are doing dirty work. 

You need to take great care in washing your hands, 
because they become soiled with all kinds of dirt, and 


THE SKIN 


T 95 


you often put them to your mouth and nose and handle 
food with them. 

Be sure to wash your hands before you eat. Never 
handle food for yourself or others without first wash¬ 
ing your hands. 

Mucous Membrane. — The lungs, the stomach, and 
the intestine are lined with an inner skin, called mucous 
membrane, which is like the skin on the outside of the 
body. The outer skin extends into the nose and 
mouth and there becomes the mucous membrane 
which extends the whole length of the air tube and the 
food tube. 

The mucous membrane consists of two layers which 
are like those of the outer skin : 

1. An epidermis. 

2. The true mucous membrane. 

The epidermis of the mucous membrane, like that of 
the skin, protects the flesh ; but unlike that of the outer 
skin, it lets some kinds of substances pass through it. 
The epidermis in the stomach and intestine takes up 
water and digested food and passes them into the blood 
tubes which lie beneath it. 

The main part of the mucous membrane is like the 
dermis of the skin. It contains numerous glands which 
are like those of the skin. They produce a fluid, called 
mucus , which is like thin white of egg. Mucus is con¬ 
stantly being formed in order to protect the surface 
of the mucous membrane and to keep it wet and smooth. 
The watery substance which you blow from your nose 



196 


THE SKIN 


is mucus. It is almost like water while you are in 
good health, but when you have a cold, it is almost 
like jelly. 


QUESTIONS 

Describe the epidermis; the dermis. 

What is a callus t a blister ? 

Why cannot substances rubbed upon the skin enter the flesh ? 

How are medicines given by means of a hypodermic syringe? 

How does the epidermis complete the healing of a wound? What 
is skin grafting f 

To what is the color of the skin due? 

What are finger prints f 

Describe a gland which forms perspiration. 

Describe a hair root. What care should you give to your hair? 

Describe a finger nail. Why should the nails be kept clean? 

What is a hangnail f 

To what is the complexion due ? How can you improve it ? 

Give some reasons for bathing. 

Why should you wash your hands before you eat ? 

What is the mucous membrane? Compare it with the skin. 

For the Teacher. — The subject of the skin is taken up in some detail 
because of the erroneous impressions produced by popular articles on the 
care of the skin, and by fantastic advertisements of impossible skin food3, 
complexion clearers, beauty restorers, pore cleansers, and hair stimulants. 
The object of this chapter is to set forth briefly the simple truth about the 
structure and action of the various parts of the skin, and the nature of the 
common skin disorders, such as corns, blisters, and freckles. 

Emphasize the need of washing the hands thoroughly before eating or 
handling food, in order to avoid transferring disease germs from the dirty hands 
to the food. 


CHAPTER XVII 


THE WASTES OF THE BODY 


Intake and Outgo. — New substances enter the body 
every day, and other substances leave it. The daily 
intake of the body of a grown person of average size is 
about as follows: 


Food (except water) i pound 


Water 

Oxygen 


6 pounds 
ij_ pounds 


Total intake 


If all the substances which enter the body remained 
there, a person would gain eight and a half pounds 
weight every day. But the weight of a grown per¬ 
son remains about the same for months or years, and 
therefore the body must give off as much matter as it 
receives. The outgo of the body almost balances its 
intake. 

Excretions. — Most of the substances which are 
given off from the body are those which have been oxi¬ 
dized in order to supply heat and power to the body. 
They are of no further use, but are waste substances 
which are thrown off. The waste substances of the 
body are called excretions . 


197 



198 


THE WASTES OF THE BODY 


The principal excretions of the body are: 

1. Water. 

2. Carbon dioxide. 

3. Urea, and similar substances. 

4. Minerals. 

Organs of Excretion. — The body gets rid of waste 
matters by means of five organs of excretion , namely : 

1. The lungs. 

2. The skin. 

3. The kidneys. 

4. The liver. 

5. The intestine. 

The lungs give off most of the carbon dioxide which 

the body produces. They 
also give off about one 
fifth of the water which 
leaves the body. Some 
of the water in the breath 
may be seen like a little 
cloud on a cold day. 

The skin gives off 
water, urea, and minerals 
by means of the perspi¬ 
ration. The salty taste 
of perspiration comes 
from the minerals which 

(Half its natural size.) A kidney is a ^j*e dissolved in it 
gland which takes water, urea, and miner¬ 
als from the blood. Most of the urea, min¬ 

erals, and water which leave the body are given off by 



A Kidney Cut in Half 




THE WASTES OF THE BODY 


199 


a pair of organs, called kidneys , which lie in the back 
part of the body below the lungs. The kidneys are 
glands and consist of tubes which are like very long 
and folded perspiratory glands (p. 190). They pro¬ 
duce a liquid, called urine (u'rm), which consists of 
minerals, urea, and other waste matters, dissolved in 
water. Drinking an abundance of water helps the 
kidneys and skin to get rid of their excretions. 

Excretion by the Intestine. — The intestine, or bowel, 
is the lower part of the food tube. It gives off two kinds 
of waste substances: 

1. Those, such as bile, which are formed by the liver 
and other glands. 

2. Those parts of food which are not digested or used 
by the body. 

Waste matters are always being formed in the intes¬ 
tine, whether food is eaten or not; and getting rid of 
them at least once a day is one of the most important 
means of caring for health. They are harmful to the 
body when they are first formed, and when they lie in 
the intestine, changes occur which make them still more 
harmful. It takes one or two days for the waste mat¬ 
ters and food to pass through the whole length of the 
food tube. If they lie in the intestine too long, they 
decay and putrefy as they would if they were lying in 
a warm, moist place outside of the body. Decaying 
matter in the intestine is a common cause of headache, 
stomach sickness, coated tongue, and bad breath. 

Go to the toilet every morning after breakfast 


200 


THE WASTES OF THE BODY 


whether you feel like it or not. If you do this, your 
intestine will learn to empty itself regularly every day. 
Training and exercising the bowel to empty itself is 
better than taking medicines for that purpose. 

Effect of Food. — The food that is eaten has a great 
effect on the excretions of the intestine. If all the food 
which is eaten is digested and taken into the blood, none 
will be left in the intestine to decay and produce harm¬ 
ful wastes. If too much food is eaten, some will not be 
taken up by the blood, but will lie in the intestine until 
it decays and becomes poisonous. Eating too much is 
one of the most common causes of sickness. Not eat¬ 
ing a food at all is better than taking medicine to get rid 
of it after it has been eaten. 

Children often eat too much candy, and grown people 
often eat too much meat. The sugar which is not di¬ 
gested turns sour, and the meat decays in the intestine, 
just as it decays outside of the body. But both sugar 
and meat are good foods and will agree with a person 
who takes only as much as the body can use. 

Need of Indigestible Food. — The intestine needs to 
be partly filled with solid matter which will push the 
waste matters forward and sweep them from the food 
tube. Every person needs to eat some food which 
leaves a large amount of solid waste that does not decay 
readily. Coarse vegetables, such as lettuce, celery, 
spinach, and cabbage, may be used. Whole-wheat 
bread also is valuable, for it contains a large amount of 
bran, or the papery husks of the wheat kernels. Al- 


THE WASTES OF THE BODY 


201 


though these foods contain a great deal of indigestible 
wastes, yet they are wholesome and necessary, for they 
help the intestine to get rid of its waste matters. 

Excretions of Nose and Throat. — The nose and 
throat are organs of excretion, for their mucous mem¬ 
brane forms mucus which we cough up from our air tubes 
or blow from the nose. Only a small amount of mucus 
is formed during health, but a large amount is often 
formed during sickness. When a person has a cold, or 
sore throat, or pneumonia, or other disease of the air 
tubes, the mucus is of great importance, for it may then 
contain germs of the disease. 

Disease Germs in Excretions. — Excretions which 
have left the body may still be harmful or dangerous, 
for they may contain disease germs. When one has a 
disease which is catching, its germs are given off with 
two sets of excretions : 

1. Those of the nose and throat. 

2. Those of the intestine and kidneys. 

A very small amount of an excretion may contain 
great numbers of disease germs. Not every person gives 
off disease germs with his excretions, but the germs may 
come from those who are only mildly sick, and from 
those who are almost well; and so we may suspect that 
the excretions of any person may contain disease germs. 
It is necessary to dispose of excretions in such a way 
that they cannot reach the body again, or its food, or 
drinking water. 

Soiled hands and fingers often carry excretions and 



202 


THE WASTES OF THE BODY 


disease germs from one person to another. A very small 
amount of an excretion with millions of disease germs 
in it may cling to the fingers and may reach milk or 
other food which is handled. When food has spread a 
disease, its germs have usually come from the soiled 
hands of those who handle the food. 

Always wash your hands after going to the toilet. 

Disposal of Excretions of the Nose and Throat. — 
Disease germs in the excretions of the nose and throat 
are often as numerous and dangerous as those in the ex¬ 
cretions of the intestine and kidneys. Most persons 
have a fear of the excretions of the intestine and kid¬ 
neys, and are careful to get rid of them in a way that is 
safe and clean; but people are often careless with the 
excretions of the nose and throat. They spread disease 
germs when they spit on floors and sidewalks; they 
blow disease germs into the air when they cough and 
sneeze; and they carry them around on handkerchiefs 
which are dirty. Mucus from the nose and throat is 
the principal cause of colds, sore throat, influenza, and 
pneumonia. 

Y ou can easily keep from spreading the excretions of 
the nose and throat if you will follow these rules: 

1. Carry a handkerchief with you and use it. When 
it becomes soiled, get a clean one. 

2. Hold your handkerchief in front of your nose and 
mouth when you cough or sneeze. 

3. Blow your nose on your handkerchief. Keep 
your nose clean and free from mucus. 


THE WASTES OF THE BODY 


203 


4. Spit in some place from which the mucus cannot 
escape. Do not spit on a floor or sidewalk. 

5. Take care of the handkerchiefs, towels, dishes, 
bedclothes, and other things which are soiled by ex¬ 
cretions of the nose and mouth. Wash them in boiling 
water in order to kill the disease germs which may be on 
them. 

Sewage. — The waste water and slops from bath¬ 
rooms, kitchens, laundries, and stables are called sewage. 
Nearly all sewage contains excretions from human be¬ 
ings ; and it will contain disease germs when it contains 
excretions from a person who has an infectious dis¬ 
ease. It often spreads diseases in two ways : 

1. By flowing into drinking water. 

2. By being carried to food or to the mouth and nose 
by flies or by other means. The safe disposal of sewage 
is one of the most important matters with which the 
people of cities and towns have to deal. 

Sewage Disposal and Decay. —• The final disposal of 
excretions, sewage, and other household wastes is 
nearly always done by means of the natural process of 
decay which is carried on by bacteria (p. 43). This 
process is closely connected with that of oxidation (p. 
38). If oxygen cannot reach the decaying substances, 
gases are formed which have foul odors, and the process 
of decay is then called putrefaction; but if oxygen 
reaches every part of the decaying matter, the products 
of decay do not have very foul odors. 

Substances which are buried in the ground usually 



204 


THE WASTES OF THE BODY 


decay and become a part of the soil without being offen¬ 
sive. The soil contains oxygen, and also bacteria which 
cause the oxygen to unite with the buried substances. 
Most substances which decay in the soil are oxidized as 
completely as if acted upon by fire ; and the only parts 
which are left are their minerals, or ashes. The dis¬ 
posal of excretions, and of sewage, garbage, and other 
household wastes, usually consists in causing them to 
decay and return to the soil in a harmless manner. 

Disease germs which may be in excretions soon die 
when the excretions become decayed and oxidized. 
The proper disposal of sewage will not only remove its 
offensive substances, but it will also kill all disease germs 
which may be in the excretions. 

Filter. — The soil also purifies sewage and other liq¬ 
uids by a process called filtra'tion. A substance which 
screens fine particles from a liquid is called & filter. The 
soil is a great filter. When sewage or other liquid passes 
through it, the sand and clay screen out the solid 
particles and hold them back, but allow the liquid parts 
to pass through. While the liquid is soaking through 
the ground, the bacteria in the soil oxidize and destroy 
both the solid particles which are held back, and also 
the liquid impurities which are dissolved in the water. 
The purification of sewage consists of a combination of 
the three processes of decay, oxidation, and filtration. 

Disposal of Sewage in the Country. — The waste 
water of houses in country places is usually thrown upon 
the ground and quickly becomes purified. House slops 


THE WASTES OF THE BODY 


205 


nearly always contain substances which may decay and 
produce foul odors. They also often contain human ex¬ 
cretions and disease germs. When they are thrown 
upon the ground, they may soak into the soil and their 
impurities may be removed and destroyed by the pro¬ 
cesses of decay, oxidation, and filtration which take 
place in the soil. Only pure water usually passes deep 
into the earth. Underground water is nearly always 
pure unless a great deal of dirty water is poured upon 
the ground in one spot. 

A common fault in the disposal of house slops is to 
allow slops and laundry water to flow upon one spot of 
ground until the soil is soaking wet and the useful bac¬ 
teria of the soil are drowned from want of oxygen. The 
water may then pass through the soil unpurified, and 
may carry waste matters to the underground water ; - or 
it may form a muddy pool from which disease germs may 
be carried by flies and other vermin. A good way to 
get rid of house slops is to catch them in a pail or barrel, 
which is emptied in the back yard, first on one spot 
and then on another, so that no spot receives more 
than it can quickly purify. 

Cesspool. — If a house has plumbing, and a supply 
of running water, the amount of sewage will be so 
large that it cannot be safely emptied upon the surface 
of the ground. A simple way to dispose of the sewage 
is to empty it into an underground tank called a cess¬ 
pool. There its solid parts and other impurities slowly 
decay, and its liquid filters away through the soil. A 


206 


THE WASTES OF THE BODY 


cesspool which is properly built, and which acts prop¬ 
erly, will destroy the disease germs which may be in the 
sewage. 

If a cesspool receives more sewage than the soil can 
purify, the sewage will reach the underground water and 
make it unfit for use. The underground water in vil¬ 
lages is seldom pure if cesspools are used. 

Sewage from a cesspool may flow along an under¬ 
ground rock or a layer of water-tight clay, and reach a 
well from which drinking water is taken. If a cesspool 
and a well must both be placed in the same yard, lo¬ 
cate the well in a place from which both the surface 
of the ground and the underground rock slope away. 
Another danger from a cesspool is that flies may carry 
disease germs away from it, or mosquitoes may breed in 
it. A cesspool is not safe unless it is covered so closely 
that flies and mosquitoes cannot enter it. 

Sewers. — Cities and large villages make more sewage 
than cesspools can safely receive. In these places the 
sewage is taken away by means of underground pipes, 
called sewers , which are built at public expense. The 
sewage from a small city would make a good-sized 
stream, and that from a large city, like New York, 
would make a river. It is difficult to get rid of this 
great quantity of sewage. 

Many cities, such as New York, Albany, and Troy, 
empty their sewage into the nearest body of water. 
But the sewage makes the water impure, and spoils it 
for the people of other cities who wish to use the river 


THE WASTES OF THE BODY 


207 


water for drinking or washing. The people of the city 
of Albany take their drinking water from the Hudson 
River, and have been put to great expense in removing 
the sewage which is poured into the river from the city 
of Troy. 

Sewage Disposal Plant. — One of the most necessary 
public works for a city or large village is a sewage dis- 



Sand Filter Beds of a Sewage Disposal Plant of a Small 

Village 

Troughs spread the sewage evenly over the surface. 


posal plant which purifies the sewage. A sewage dis¬ 
posal plant which acts properly will destroy the disease 
germs which may be in the sewage. 

One of the best forms of sewage disposal is to collect 
all the sewage into a large water-tight cesspool, called a 








208 


THE WASTES OF THE BODY 


septic tank , where its solid parts decay and become lique¬ 
fied as in a small cesspool. The liquid which overflows 
from the tank is then emptied on plots of sand, first 
on one, and then on another, so that each plot is used 



Sprinkling Sewage upon a Bed or Broken Stone 

Mixing sewage with oxygen destroys much of the bad odor. 


only once a day. The soil of the sand plots acts like a 
filter and destroys the impurities in the sewage, just as 
the soil does when a basin of slops is thrown on the 
ground in a back yard. This method of getting rid of 
sewage is almost like nature’s own way of purifying 
dirty water. A sewage disposal plant that is run prop¬ 
erly is no more unpleasant to sight or smell than a 
stable or barnyard. 

In some sewage disposal plants the impure water 
which flows from a septic tank is sprayed upon large 
beds of broken stone before it flows upon the soil. 
The stone bed causes the sewage to be mixed with oxy¬ 
gen, and its impurities to be oxidized and destroyed. 

Gas Trap. — The pipes which carry waste water 
away from houses are laid sloping so that the water will 







THE WASTES OF THE BODY 


209 



quickly run out of them. The waste pipes are nearly 
always empty, and are likely to let foul-smelling gases 
into the room, unless they have arrangements, called 
traps , to keep the gases out. 

In a common form of trap, the upright part of the 
waste pipe under 
a tub or basin is 
bent in the form of 
a deep loop. When 
the tub or basin is 
emptied, the loop 
of the pipe remains 
full of water, and 
prevents gases from 
escaping. The 
plumbing of a house 
will be unsafe un¬ 
less there is a trap 
in each waste pipe 
under the sinks, 
bathtubs, and ba¬ 
sins. 

Garbage. — The solid waste matter from a kitchen is 
called garbage. It consists of such things as scraps of 
food, potato peelings, meat rinds, bones, dirty tin cans, 
and ashes. These are often thrown in a pile behind an 
outbuilding. Slops are often thrown over them, mak¬ 
ing a foul mass in which disease germs live. House 
flies often flit back and forth between the pile and the 


Gas Trap 

When water runs out of the basin, the loop re¬ 
mains full and prevents gases from passing up 
the pipe and into the room. 


OV. GEN. HYG.—-14 









210 


THE WASTES OF THE BODY 


kitchen, and carry filth and disease germs to food. A 
garbage heap is dangerous to health. 

You can easily get rid of garbage without throwing it 
into heaps. Feed scraps of food to chickens or pigs, or 
burn them. Burn or bury everything else that will 
decay. 

In many cities, the garbage is collected at public ex¬ 
pense and sorted. Much of it is put to use so as to help 
pay the cost of its disposal. For example, grease and 
fat are preserved for soap making, and wood and paper 
are burned under steam boilers. 

QUESTIONS 

What quantity of substances enters and leaves the body every day? 

What is an excretion? Name the principal excretions; the prin¬ 
cipal organs of excretion. 

What substances are excreted by the lungs? by the skin? by 
the kidneys? by the liver? by the intestine? 

Why is some indigestible food needed in the intestine? 

Why are the excretions of the nose and throat dangerous? How 
can you dispose of those excretions in a safe way? 

What is sewage? 

What are the dangers from sewage? 

What is putrefaction? 

How does the soil destroy sewage and other waste substances? 

What is filtration? 

Describe the natural process of purifying slops and sewage when 
they are thrown upon the ground. 

What is a cesspool? 

What are the dangers from a cesspool? 

What is a septic tank ? 

Describe a simple sewage disposal plant. 

Describe a gas .trap in house plumbing. 


THE WASTES OF THE BODY 


211 


Of what does garbage consist ? 

How can garbage be disposed of in a safe way? 

For the Teacher. — This chapter gives a bird’s-eye review of the subject 
of excretions from the time of their production in the body to their final dis¬ 
posal in sewage and household wastes. The following topics need to be spe¬ 
cially emphasized because they are not generally discussed: 

Disease germs in the excretions and the danger from them after they have 
left the body. 

Methods of disposal of the excretions of the nose and mouth. 

Safe methods of the disposal of the excretions of the intestine and the 
kidneys. 

Sewage disposal in the soil by the natural processes of decay, oxidation, and 
filtration. 

It would be desirable to discuss the proper construction and care of outdoor 
toilets and cesspools. Lay stress on the necessity of making them fly-tight, so 
that flies and other vermin cannot enter them. Also call attention to the possi- 
bility of unpurified water from them reaching a water supply which is used for 
drinking. 

Call the attention of the class to the sewage disposal system of the school and 
mention its good points as well as its defects. Try to induce the school authori¬ 
ties to maintain the toilets and other devices in a model sanitary state, as an ex¬ 
ample for the people of the community. 


CHAPTER XVIII 


WATER SUPPLY 

Quantity of Water Needed Daily. — Each grown 
person needs about three quarts of water to replace 
that which passes off from the body each day. One 
or two gallons of watef will be needed for preparing 
and cooking the food, and for washing dishes; and 
at least another gallon will be required in washing and 
bathing the body. Each person requires at least 
three gallons, or one large pailful, of water each day. 

In many families each person uses at least five gal¬ 
lons a day in bathing, laundering, and house cleaning. 
If the house has a bathroom, this quantity will be much 
more than doubled. A great deal of water is also used 
in stables and in the care of animals. A city has to 
supply at least thirty gallons a day for each person. 
London supplies thirty-five gallons a day for each in¬ 
habitant. New York supplies two or three hundred 
gallons, but much of it is wasted. 

Source of Water Supplies. — The simplest way to 
get a supply of water is to take it from a natural spring, 
or stream, or lake. Another way is to dig or drive a 
well, so as to reach the underground water. Another 



WATER SUPPLY 


213 


way is to catch rain water from a roof and store it 
in a cistern. 

Those who live in cities and large towns draw water 
from pipes which connect with the public waterworks, 
but the water usually comes from streams or lakes, or 
underground sources. 

There are differences in the taste and appearance of 
water from various places. The differences are due to 
substances which are contained in the water. 

What Is in Water. — Water always has substances 
dissolved in it. The purest water is rain water, but 
that has air in it. If we could get water with nothing 
dissolved in it, we should not like it, for the pleasant 
taste of good water comes largely from the air which 
is dissolved in it. 

Boil some water in a clean kettle for five minutes. 
It will taste flat and unpleasant, for most of its air has 
passed off with the steam. Now stir or shake it to a 
foam so that it will become mixed with air. It will now 
taste like fresh water again. 

Underground water, and the water in springs, 
streams, and lakes, come from rain or snow. As the 
water soaks through the ground, it dissolves lime, salt, 
and other minerals from the soil. Nearly all under¬ 
ground water has a little lime and salt dissolved in it. 

Let a drop of clear water dry on a clean glass. It 
will leave a whitish spot of minerals which had been 
dissolved in the water. You can often see these spots 
of minerals on a window after it has been washed. 


214 


WATER SUPPLY 


Soft and Hard Water. — The minerals in water are 
often too small in quantity to be noticed. Such water 
is called soft water. 

In some places the water has so much lime dissolved 
in it that the minerals form a scum when soap is added 
to the water. Such water is called hard water. The 
minerals in hard water do not make it unfit for drink¬ 
ing. Hard water is sometimes not good for cooking, 
for some foods, such as peas and beans, do not easily 
become soft when they are boiled in it. 

Mineral Water. — Water in which many mineral 
substances are dissolved is called mineral water. 
Some mineral waters are bubbling full of carbon dioxide 
which gives them a pleasant taste and a sparkling ap¬ 
pearance. Some waters contain sulphur, or iron, or 
potash, or other minerals which are used as medicines. 
The good effects of drinking mineral water come from 
the water itself as much as from the minerals which 
are dissolved in it, for many persons who usually drink 
too little water will drink large quantities of mineral 
water. 

Impurities in Water. — Much of the water which 
is used in houses contains either pieces of wood and 
leaves, or bits of iron rust, or particles of clay and mud. 
A little of them will do no harm, but if the water is 
muddy, or colored, or tastes bad, it will be likely to 
harm those who drink it. 

Almost the only dangerous impurities in water are 
disease germs. The principal reason why dirty water 





WATER SUPPLY 


215 


is harmful is because disease germs are often found in 
the dirt. But disease germs may be in water which 
is clear and sparkling, and pleasant to the taste. 

How Disease Germs Get into Water. — Water will 
not produce a disease unless it contains living germs 
of the disease. Disease germs are not produced by 
dead leaves, or grass, or sticks, or mud. They are 
formed only in the bodies of sick persons or animals. 
If they are in water, it is because they came there with 
sewage containing the excretions from a sick person or 
a sick animal. Keeping water pure means keeping it 
free from sewage and from dirty water from houses 
and barnyards. Nearly all the dangerous impurities 
in water come from human beings. 

Diseases Caused by Impure Water. — The principal 
kinds of disease germs which are found in impure water 
are those which cause stomach aches, typhoid fever, 
and other diseases of the intestine. Most rivers which 
flow past farms or towns contain sewage, and many 
of the people who drink the water of the rivers are 
made sick, unless the water is purified before it is used. 
Hundreds of people die each year in the United States 
from typhoid fever which is caught from drinking 
water containing sewage. Nearly all of these deaths 
are due to carelessness and neglect, and could easily 
be prevented by proper care of sewage. In one 
small city over a thousand persons caught typhoid 
fever because the slops from a person sick with typhoid 
fever were thrown upon a frozen hillside, and later 



2 l6 


WATER SUPPLY 


were washed into the river which supplied the city 
with drinking water. 

Pure Drinking Water in the Country. — People in 
the country usually get their drinking water from wells 
which are sunk into the underground water. This 



An Unsafe Well 


It is open at the top, and barnyard drainage can flow into it through its lining. 


water is nearly always pure, unless some ignorant or 
careless person allows excretions, or slops, or barn¬ 
yard drainage to run into the well, or into the under¬ 
ground water which feeds it. 

Many wells are unfit for use because they are placed 
over underground streams of dirty water flowing from 







WATER SUPPLY 


217 


cesspools, or wet barnyards, or from dumping places 
for slops and excretions. The place for a well is on the 
highest part of a yard, so that all dirty water, both from 
the surface and from under¬ 
ground, will flow away from it. 

If a spring or well is open 
at the top, or has sides of 
• brick or stone, dirty surface 
water, worms, and other im¬ 
purities may fall into it, or 
may drop through cracks in 
the bricks or stones. An old- 
fashioned open well is not 
safe, even if the underground 
water is pure when it flows 
into the well. A well made 
oy driving a small iron pipe 
into the ground is safe if the 
underground water is pure, 
for no dirt can fall down it. 

Pure Drinking Water in Cities. — The people of 
cities have their water brought to their houses through 
aqueducts and pipes which are fed from public water¬ 
works. If the water in the works is pure, the water in 
the houses will also be pure, for nothing can get into 
the pipes except that which comes from the water¬ 
works. 

Many cities take their water from rivers or lakes 
which contain sewage. If they do not purify their 



A Driven Well 
Nothing can fall into it. 





2 l8 


WATER SUPPLY 


water, they have more typhoid fever than those which 
do purify it, or which take their water from pure 
sources. In the city of Albany, during the ten years 
following the year 1900, there was only one fourth as 
much typhoid fever as there was during the ten years 

before 1900, be¬ 
cause since 1900 
the water has been 
purified before be¬ 
ing sent through 
the city. 

Reservoirs. — 

One way of purify¬ 
ing drinking water 
is to store it in a 
reservoir for a few 
days. The dirt and 
mud, and most of 
the bacteria, will 
sink to the bottom, 
and the sunlight 

will kill many of 
the bacteria. A 

reservoir is a great help in purifying drinking water, 
but it alone will not make impure water entirely safe. 

Filtration. — One of the easiest and best ways of 
purifying water is to pass it through a large bed of 
sand, called a filter, which strains out dirt and bacteria. 

The soil is a great filter (p. 204). If a filter is very 



In the Catskill Aqueduct 

This shows one part under construction as a tun¬ 
nel. The completed aqueduct supplies the city of 
New York with pure water. 









WATER SUPPLY 


219 


large, and the water passes through it slowly, it will 
take out very nearly all the dirt and disease germs that 



may be in the water. Albany, Philadelphia, and many 
other large cities which have to take their water from 



One of the Albany Filter Tanks, with the Water Drawn Off 

It contains about three feet of sand, above which the water is allowed to lie about 
three feet deep, and to pass slowly down through the sand. 


impure rivers, pass the water through great filters, in 
order to purify it. 













220 


WATER SUPPLY 


If a filter is small, or if water is run rapidly through 
it, the flow of water will wash bacteria and disease 
germs through it as if it were a sieve. For. this reason 
the* small filters sold for use in kitchens will not purify 
the water. 

Purifying Water by Boiling. — If drinking water is 
not pure, we can make it safe for use by boiling it, for 
a boiling heat will kill the disease germs. Many per¬ 
sons who fear to drink plain water drink tea or coffee. 
The tea or coffee which is added to the water does not 
make the water safe, but the heat of boiling the drink 
kills the disease germs in the water. The Chinese are 
able to drink dirty river water with safety, because 
they boil the water which they drink, and cook all 
their food before eating it. 

Water which has been boiled for some minutes tastes 
bad, because the boiling drives the air from it (p. 213). 
If the water is taken from the fire as soon as it begins 
to boil, the disease germs which may be in it will be 
killed, but the water will not lose much of its air, and 
its taste will not be changed. 

Purification by Chlorine. — Adding liquid chlorine 
(klo'rin) to water is the usual method of treating 
suspected water in order to make it safe for drink¬ 
ing. The chlorine acts by killing the disease germs 
and other bacteria which may be in the water. Many 
villages and cities which take their water from streams 
and lakes treat the water with chlorine in order to be 
sure that the disease germs in it are killed. 



WATER SUPPLY 


221 


Ice. — Ice taken or made from impure water will con¬ 
tain disease germs if the water contained germs before it 
froze. Those who work or skate on the ice may leave 
disease germs, on it, or the ice may be soiled by the 
dirty hands or dirty clothes of those who handle it. 
Cold will not kill the germs, and they will grow as soon 
as the ice melts. The purity of the ice which is put 
into food and water is of as much importance as the 
purity of the food and the water themselves. 

Washing with Impure Water. — Impure water which 
is used in bathing the body or in washing dishes may 
be the cause of spreading diseases. Milk cans which 
have been washed in impure water have often been 
the cause of typhoid fever in those who have taken 
milk from the cans. It is almost as dangerous to use 
impure water for washing as for drinking. 

Examining Water. — The purity of a water supply 
may be determined in three ways : 

1. By a sanitary survey. 

2. By a chemical analysis. 

3. By a bacteriological examination. 

Sanitary Survey. — Most water in wells, springs, 

streams, and lakes is naturally pure and wholesome, 
and will remain so unless excretions from human 
beings or animals reach it. The sources of possible 
impurities may be easily found by means of a san¬ 
itary survey of the source and the land around it. 
When a sanitary survey is made, the following points 
are to be observed: 





222 


WATER SUPPLY 


1. The source itself, — a well, cistern, stream, lake, 
etc. If it is a well, notice its construction, state of 
repair, and the means for keeping dirt and waste 
water from falling into it. 

2. The soil around the source. Is it high or low? 
sandy or clayey? grassy or bare? level or sloping? 
inhabited or deserted ? 

3. Possible sources of pollution by excretions. 
Notice kitchen waste, toilets, cesspools, drains, barn¬ 
yards, and cultivated fields near the water. 

Chemical Analysis. — A chemical analysis will show 
the kinds and amounts of substances which are dis¬ 
solved in a water sample. Minerals are dissolved in 
nearly every water, and their kind and amount in any 
place naturally continue nearly the same from time 
to time. Almost the only things which are likely to 
increase the amount of minerals are sewage and barn¬ 
yard drainage, especially the excretions of men and 
animals. One of the most common of the minerals in 
excretions is sodium chloride (so'di-um klo'rld), or com¬ 
mon salt. If the amount of salt in water from a cer¬ 
tain source is greater than that which is natural for that 
place, the extra amount has probably come from sewage. 

Bacteriological Examination. — Most water natu¬ 
rally contains a few living bacteria of decay which 
come from the air and soil. Only a few hundred are 
found in each cubic centimeter of clear, wholesome 
water, but the presence of several thousand shows that 
decaying matter is in the water. 




WATER SUPPLY 


223 


Water is also examined for living bacteria of the 
intestine, or co'lon bacilli (ba-silfi). Their presence 
shows that fresh excretions from the intestines of per¬ 
sons or warm-blooded animals are reaching the water, 
and that living disease germs may also be in the 
water. 

Colon bacilli in water may come from three sources: 

1. Animals or birds. 

2. Surface drainage from roads or cultivated fields. 

3. Sewage or barnyard drainage. 

A sanitary survey will show which of these sources 
is producing the colon bacilli. 

An increase in the amount of salt, if colon bacilli are 
absent, shows that sewage is probably entering the 
water, but that its impurities are fully oxidized to 
ashes or mineral matter. Such water may be pure 
and wholesome, but it may become unwholesome if 
the amount of sewage is increased. 

An increase of salt in water, if living colon bacilli 
are present, shows that fresh, unpurified excretions are 
reaching the water, and that the water may contain 
living disease germs. 

Public Drinking Cups. — Drinking cups are often 
placed in schools, in railroad trains and stations, and 
in public buildings, to be used by any one who wants a 
drink. Every person who takes the cup between his 
lips leaves mucus, epithelial cells, and bacteria from 
the mouth upon the rim of the cup, and the next 
person who drinks from the cup takes some of them 


224 


WATER SUPPLY 




Paper Drinking Cups 


into his mouth, and leaves more from his own mouth 
upon the cup. Some one who has a cold, or a sore 

throat, or a worse disease, is 
almost sure to use the cup and 
to leave disease germs upon it. 
Tuberculosis and diphtheria 
are two diseases which are likely 
to be spread by the use of the 
cups. Public drinking cups 
are so dangerous that some 
states have laws that none shall be placed in any 
public place in those states. 

Paper drinking cups are often placed in public drink¬ 
ing fountains, to be thrown 
away as soon as they have 
been used. They are for 
sale at drug stores and sta¬ 
tionery stores. They are 
cheap and may easily be 
carried. Take some with 
you and use them when 
you go away from home, 
or when you start on a 
journey. 

If you must use a public 
drinking cup, do not take 
the rim between your lips, 

but touch both lips to the water inside the rim. Thus 
your lips will touch nothing except the water of the cup. 


A Safe Drinking Fountain 

The nozzle is at the side where no one 
can touch it. 















WATER SUPPLY 


225 


Bubbling Drinking Fountains. — Schools and other 
public places often have drinking fountains in which 
the water bubbles up in a stream. Some of these 
fountains have two defects : 

1. A person drinking can touch his lips or mouth 

1 

to the fixtures. 

2. Excretions from the mouth may fall on the fix¬ 
tures. 

A safe form of drinking fountain is one in which a 
jet of water spouts sidewise in a stream from a fixture 
which is covered with a shield. A person drinks from 
the outer part of the stream and cannot drop excre¬ 
tions upon the fixture. 


QUESTIONS 

How much water does a man need to take into his body each day ? 
About how much water will each person in a family use in a day ? 
Of what use is air in water? 

What is meant by hard water? What are mineral waters? 

Of what do the common impurities in water consist ? 

What are the most dangerous impurities in water? 

How do disease germs get into water? 

What diseases are often caused by impure water? 

Why is water from an open well not so safe as water taken from a 
driven well? 

How does storing water in a reservoir help to purify it? 

What is a filter? 

How does boiling purify impure water? 

How may ice be a means of spreading diseases? 

Plow can you tell whether or not a water supply is pure ? 

For what conditions would you look if you should make a sanitary 
survey of a source of water? 


OV. GEN. HYG. — 15 



226 


WATER SUPPLY 


When a chemical analysis of water is made, what substance indi¬ 
cates that sewage has entered the water? 

What do colon bacilli in water indicate ? 

What harm is often done by the use of public drinking cups? 
Give some reasons for using paper drinking cups. 

Describe a safe form of drinking fountain for schools. 

How can you drink from a public cup with the least danger? 


For the Teacher. — The standards for a household water supply are: 

1. The water shall be clean and clear. 

2. It shall not be excessively “ hard.” 

3. It shall be free from disease germs. 

From the standpoint of hygiene, disease germs are the most impor¬ 
tant impurities in water. Their source is human excretions and household 
sewage. The principal diseases which are spread by drinking water are those 
which affect the intestine. 

The examination of water supplies is conducted along three lines: 

1. A sanitary survey of the source of the supply and the country around 
it is made in order to see if there are any houses, toilets, cesspools, sewers, 
or barnyards from which excretions could come. 

2. A bacteriological examination of a sample of the water is made in order 
to determine the presence of colon bacilli. 

3. A chemical examination of a sample of the water is made in order to 
determine the quantity of the special mineral matters of human excretions and 
sewage. Most water contains some of these minerals which are derived 
from such sources as fertilizers thrown upon the soil, but an excess of these 
peculiar minerals shows that sewage is reaching the water. 

When a village or city grows so much that wells on its outskirts become 
polluted with sewage, repeated analysis of the water will show the progress of 
the pollution. The water will first show increasing amounts of minerals, 
and later when the limit of the purifying ability of the soil is reached, colon 
bacilli will appear, and the water will be dangerous for household use. 

Demonstrate the process of filtration by filling a lamp chimney two thirds 
full of garden soil, standing it in a pan, and adding muddy water until the 
chimney is full. The water which oozes from the bottom of the chimney will 
be nearly clear. In order to purify water efficiently, the water must pass 
through the filter slowly, as it does through the soil after a rain. 

Be sure to make a practical application of this chapter to the water supplies 
of your school, the homes of the pupils, and the public supply of the village or 
city. Have the pupils visit the source of the supplies and notice the possible 
sources from which pollution might reach the water. If possible, obtain an 
analysis from the health officer, and explain it to the pupils. 


CHAPTER XIX 


VERMIN 

How Insects Cause Diseases. — Men used to think 
that flies, mosquitoes, and other insects did not 
harm a person beyond causing a tickling and itching 
when they bit the skin. It is now known that 
many of them are disease carriers, and are dangerous 
to health and life. Nearly all insects that bite the 
body may carry diseases from a sick person or animal 
to the next person or animal whom they bite. The 
most common and most dangerous insects that affect 
the health are flies, mosquitoes, cockroaches, lice, bed¬ 
bugs, and fleas. Insects and other small animals which, 
are troublesome to man, or are harmful to health, are 
called vermin. 

Bee Stings. — The stings of bees and wasps cause 
swellings which are painful for a short time, but they 
are not the cause of any disease, for bees and wasps do 
not go from person to person as flies and mosquitoes 
do. Most insects which are harmful bite in order to 
get food, but bees and wasps sting only to protect them¬ 
selves from harm. If one buzzes around your head, it 
will not touch you if you keep still and do not annoy it. 


227 


228 


VERMIN 


A bee stings by means of a hollow spear which it 
thrusts into the skin from the hinder part of its body. 
The spear itself is too small to hurt, but the bee uses 
it to force a bit of poison into the skin. This poison 
is what causes the swelling and the pain of the sting. 
You can relieve the pain somewhat by pinching the 
skin so as to squeeze the poison out of the flesh. Cold 
water, or a little ammonia rubbed on the spot, will 
also help to relieve the pain. 

Danger from House Flies. — A house fly cannot bite, 
or sting, or scratch, and yet it is dangerous because of 

the places which it visits 
in search of food. It lights 
upon garbage heaps and ex¬ 
cretions, and in dirty stables, 
where its legs and body be¬ 
come soiled with filth and 
disease germs. It then flits 
into houses and crawls 
upon food and over the 
mouths and eyes of helpless 
babies, dropping disease 
germs wherever it goes. 
The blue flies, which may 
often be seen swarming over decaying meat, may also 
be the carriers of disease germs. 

A fly’s body and legs are covered with stiff hairs, 
which catch dirt and filth. Under a microscope the 
fly looks like a bristly pig that has been wallowing in 






VERMIN 


229 


the dirt. It tries to keep itself clean, for it often rubs 
its feet together, and brushes its front legs over its 
head, as a cat does. But it 
is usually covered with bac¬ 
teria which it gets from the 
dirty places where it alights. 

Shaking a fly in a bottle of 
water will often wash more 
than a million bacteria 
from its body. A fly which 
falls into a milk pitcher 
usually leaves thousands 
of bacteria and disease 
germs in the milk. 

The most common forms 
of sickness that are spread 
by house flies are typhoid fever and other intestinal 
diseases. Many of the stomach diseases of babies are 
caused by disease germs which flies have left in 
the children’s milk or in their mouths. Sore eyes 
of a baby are often caused by flies crawling over 
the baby’s face. Tuberculosis may be spread by 
flies. 

Protection against Flies. — A house fly will not carry 
disease germs if it cannot go where it can pick them up. 
Keep flies out of all sick rooms. Cover all excretions 
and sewage fly-tight. Clean up the garbage heaps in 
the back yard, and either burn or bury all decaying 
matter. If everybody did these things, flies would 



A Fly’s Foot 


(Magnified 200 times.) It is rougher 
than the foot of an elephant, and it 
leaves tracks of dirt and bacteria 
wherever the fly crawls. 







2 3 ° 


VERMIN 


not carry diseases, for they could not get the germs 
on their bodies. 

Another method of protection against flies is to cover 
windows and doors with screens and fly netting in order 
to keep all flies out of the house and away from food. 
A swarm of flies in a kitchen or dining room is far 
more dangerous than a swarm of bees. In our war 
with Spain the number of soldiers who were killed 



Life History of a House Fly 

A fly is first an egg, then a maggot, then a pupa, and finally a winged fly. 


by house flies was five times the number of those 
killed by bullets, for the flies spread typhoid fever 
through the camps. 

Flies find their food by means of their sense of smell. 
They prefer substances which have an unpleasant odor 
of decay, and they flock to dirty garbage cans and to 
kitchens which have a strong odor of filth. Cleanli¬ 
ness of kitchens and dining rooms is a great help in 
keeping flies away from food. 





VERMIN 


231 


The Life of a Fly. — A fly lives only half of its life 
as a winged creature. During the first half of its life 
it looks like a worm, and is called a maggot. Every 
maggot in a manure pile, or garbage heap, or mass of 
decaying filth, is a young fly. 

Maggots hatch from eggs which are laid by winged 
flies in stable cleanings, wet garbage, decaying meat, 
and wet filth of all kinds. 

The “ flyblows ” which are 
often seen on decaying 
meats and garbage are the 
eggs of flies. The maggots 
reach their growth in about 
a week. Their skins then 
harden into brown shells, 
called pupa cases, which 
look like fat grains of 
wheat. The young flies 
lie quietly in the cases for 
a few days and then come 
out as full-grown flies with 
wings. 

Getting Rid of Flies. — If there were no manure 
piles, or garbage heaps, or other masses of decaying 
filth, there would be no places in which flies could 
hatch or grow. Remove all manure piles and gar¬ 
bage heaps at least once every week. Keep all stables 
and barnyards clean and dry. Doing these things 
throughout a town will rid the place of flies. 



Maggots in a Manure Pile 

(Natural size.) Every maggot is a 
young fly. 





232 


VERMIN 


The time to begin to fight flies is early in the spring. 
Only a few flies live through the winter, and all that 
are seen in the following summer are descended from 
them. Each fly lays over a hundred eggs, and the new 
brood is ready to lay eggs within two or three weeks. 
Every maggot or fly that is killed in the spring and early 
summer means thousands less flies later in the season. 

Mosquitoes and Diseases. — Certain kinds of mos¬ 
quitoes are the means of spreading malaria and yellow 
fever, and for this reason they have been the cause 
of some of the worst epidemics that the world has ever 
seen. The discovery that mosquitoes will carry dis¬ 
eases was made about the year 1900. Before that time 
it was difficult for those living in Panama and Havana 
to avoid catching malaria and yellow fever. These 
diseases have almost disappeared from those places 
since the time when the United States government 
showed the inhabitants how to destroy all mosquitoes. 

Malaria is caused by living germs which grow in the 
blood. A mosquito that sucks blood from some one 
who has malaria takes the germs into its body, and 
afterward gives them to persons whom it bites. The 
germs of malaria will live in only a few kinds of mos¬ 
quitoes, but these kinds are scattered over a large part 
of the earth, and may grow where other kinds grow. 

One way of telling a malarial mosquito is by its posi¬ 
tion when it alights, for it seems to stand on its head 
with the hinder part of its body pointing away from the 
surface on which it stands. It has spots on its wings. 



VERMIN 


233 



Yellow fever is caught in the same way that malaria 
is caught, but the mosquito which carries the germs of 
yellow fever usually grows only in warm countries, 
for freezing kills it. 

Life History of a Mosquito. — Mosquitoes hatch 
from eggs which are laid by the full-grown insects in 

an\ t Eit rmipf 

T Fv f A w V 4. ^ V/ 

water that they can 
find. The eggs are 
black, and look like 
flakes of soot float¬ 
ing on the water. 

Young mosquitoes 
are the tiny crea¬ 
tures called wigglers , 
that may often be 
seen in rain barrels 
resting at the sur¬ 
face of the water, 

. Mosquito, Eggs, and Wiggler 

and wiggling them- .. , . , . . . 

00 y (Magnified 5 times.) A mosquito lays eggs on 

Selves down into the water ; wigglers hatch from the eggs and live in the 

water, and finally turn into winged mosquitoes. 

water when they are 

disturbed. They are found in all kinds of stagnant 
water, such as marshes and mud puddles, and pails 
and cans of dirty water. Cesspools are often full of 
them, and even vases of flowers may contain them. 
About two weeks after they hatch, the wigglers 
change to winged mosquitoes which fly away, leaving 
their empty skins floating on the water. 





234 


VERMIN 


How to Get Rid of Mosquitoes. — We can get rid of 

mosquitoes by destroying them in their breeding places. 

If mosquitoes can 
find no stagnant 
water in which to 
lay their eggs, no 
young ones can 
grow. Very many 
of the mosquitoes 



Wigglers Clinging to the Surface of 
Water 



(Natural size.) The wigglers must come to the arOUlld houses are 
surface in order to breathe. 

hatched m pails, 
tin cans, and rain barrels. If these vessels of water 
are emptied once a week, young mosquitoes will not 
have time to become 
full grown in them. 

Wigglers must come 
to the surface of the 
water to breathe. If 
kerosene or other oil 
is poured on the water, 
the wigglers cannot get 
air, and they soon 
drown. A teaspoonful 
of kerosene poured 
into a barrel of rain 


Wigglers in a Ditch 

Hundreds could be scooped up with every 
dip of a teacup. 


water will kill all the wigglers in it, and will not harm 
the water for washing purposes. 

The principal breeding places for mosquitoes are 
swamps and marshes that are full of stagnant pools. 









VERMIN 


235 


We may dry up the pools by digging ditches which 
will drain off the water and leave the surface dry. No 
mosquitoes can then grow except in the ditches, and 
there they will be eaten by fish, or carried away by the 
current of water. Many of the marshes near the 
city of New York have been freed from mosquitoes by 
being drained. 

Cockroaches. — Cockroaches are long, brownish 
insects that live in cracks of kitchen floors, and among 
the water pipes, and in dark, damp places in houses. 
They do not bite persons, but they live upon garbage 
and filth, and may be the means of carrying disease 
germs to food as they crawl over it. They may be 
killed by means of insect powder. Cockroaches are not 
likely to appear, if floors of kitchens and bathrooms are 
tight, and the plumbing of the house is open and clean. 

Lice. — One of the most 
dangerous of insects is the 
louse, for it is the cause of 
typhus fever. It spreads 
the disease by sucking the 
blood of those who have 
typhus fever and carrying 
the disease germs to the 

next persons whom it bites. (Magnified 10 times.) They carry ty- 
There are two common P husfever - Head lice are also dangerous 

to health. 

forms of lice, — the head 

louse, and the body louse. Both hatch from eggs, 
called nits. 



Body Lice and Their Eggs 






236 


VERMIN 


Body lice live on the underclothes, and lay their 
eggs in the seams. Keeping the body clean and boil¬ 
ing the clothes will rid the body of the lice. The eggs 
of head lice are fastened to the hairs close to the skin. 
If the eggs are found at a distance from the skin, they 
have been laid for so long a time that the growth of the 
hair has carried them away from the skin. 

Washing the hair in strong soapsuds, to every pint 
of which a tablespoonful of kerosene has been added, 
will kill the lice, but the eggs may remain alive and 
hatch a new brood. After using the kerosene, soak 
the hair in weak vinegar in order to dissolve the glue 
which binds the eggs to the hair. The eggs may then 
be washed away, and the head entirely freed from the 
lice. 

Bedbugs. — Bedbugs are brown, flat insects about 
an eighth of an inch in length. They live by sucking 
a person’s blood, and may carry a disease, such as 
tuberculosis, from one person to another. They have no 
wings, and will not be found in a house unless some one 
brings them there. We may get rid of them by clean¬ 
liness and by searching them out and destroying 
them. 

Fleas. — Fleas are small, brown insects that move 
by long jumps. They are often found on dogs, cats, 
rats, and other lower animals. They sometimes 
jump upon the bodies of persons. They live by suck¬ 
ing blood, and may carry disease germs from one per¬ 
son or animal to another. 


VERMIN 


237 


The plague is a disease of rats as well as of mankind. 
It is usually spread by means of the bites of fleas which 
have taken the germs from diseased rats. This dis¬ 
ease killed millions of people in Europe a few hundred 
years ago, and is still found in some parts of the 
world. The principal means of preventing the spread 
of the disease in a town is by killing all the rats there. 

Rats and Mice. — Rats and mice may become sick 
with several diseases which persons may take from 
them. Besides the plague, they may also have epi¬ 
demic jaundice (jan'dis), and may spread the dis¬ 
eases to man. Both rats and mice may also carry dis¬ 
ease germs in dirt on their bodies, and may spread 
them to food and drinking water. 

Some of the means of getting rid of rats and mice 
are: 

1. Cleaning up cellars and tumble-down buildings, 
and destroying places in which the animals may hide. 

2. Making cellars and foundations of houses so 
tight that the animals cannot enter the buildings. 

3. Removing or burning heaps of garbage and rub¬ 
bish. A village dump heap is often full of rats, and 
is usually a menace to health. 

Stray Cats and Dogs. — A dog or a cat is called mad 
when it has the disease called rabies (ra/bi-ez), or 
hydrophobia (hl-dro-fo'bi-d). Rabies is caused by 
germs which grow in the brains and also in the 
mouths of the sick animals. Most of the animals and 
persons that have rabies catch it from the bites of 



238 


VERMIN 


homeless dogs and cats on the streets. A public dog 
catcher, to catch all stray dogs and cats, is an im¬ 
portant and useful officer. 

If a person is bitten by a dog or cat, do not kill 
the animal, but shut it up to see if it has rabies. 
If it has the disease, it will die within a few days. If 
it lives, it has never had rabies, and there is no danger 
that its bite will give any one rabies. 

A person bitten by a rabid animal can escape having 
the disease by taking the kind of vaccination which is 
called the Pasteur (pas-tur') treatment. You can get 
information about the treatment from the boards of 
health of the states and large cities. 

Sick Pets. — Pet animals sometimes have the same 
kinds of sickness that people have, and persons may 
catch the diseases by handling them. If your cat, or 
dog, or other pet animal is sick, do not handle it or 
leave it in the house, but give it a good bed in the 
basement or barn, and let a careful grown person 
take care of it. 


QUESTIONS 

What are vermin f Name some of the common vermin. 
How do house flies spread diseases? 

What diseases are often spread by flies? 

How may disease germs be kept from the bodies of flies? 
How can we protect ourselves against flies? 

Where are young flies found ? 

What is a maggot ? 

How may flies be prevented from developing? 

What harm is done by mosquitoes? 



VERMIN 


239 


How can you tell the kind of mosquito which produces malaria? 

What is the cause of yellow fever? 

How may malaria and yellow fever be prevented ? 

Where do young mosquitoes live? 

How can we get rid of mosquitoes? 

What harm is done by cockroaches? How can we get rid of 
them ? 

What disease may be spread by lice? What are nits? 

How may lice and nits be removed from the hair? 

What harm do bedbugs do? 

How do fleas help to spread the plague? 

What have rats to do with the spread of the plague? 

How can we get rid of rats and mice ? 

What disease is often spread by stray dogs and cats ? 

If a cat or a dog has bitten a person, what should be done with the 
animal ? 

If a person is bitten by an animal that has hydrophobia, what 
should be done to prevent him from taking the disease ? 

What should be done with a sick pet ? 

For the Teacher. — The subject of vermin is of great practical importance 
in hygiene. Insects have affected the history of nations by spreading the 
germs of malaria, yellow fever, plague, and typhus fever among the people. 
Typhus fever and plague are kept out of the city of New York to-day only by 
the great precautions which are taken against the admission of rats, fleas, and 
lice from foreign ships. 

Collect some maggots and pupas from a stable or manure pile and show them to 
the class. If a pupa is opened carefully, a young fly may sometimes be found 
ready to emerge. Show how flies may be destroyed in their breeding places. 

While not all kinds of mosquitoes spread diseases, yet all are annoying 
nuisances. Collect some wigglers and let the pupils observe them for a number 
of days and watch the full-grown mosquitoes emerge. Take the pupils to a 
marsh or rain barrel where mosquitoes are breeding and show them how the 
breeding could be prevented. Emphasize the fact that persons often grow 
mosquitoes in uncovered rain barrels and cesspools in their own back yards. 

Head lice may spread disease just as body lice may spread it. A standard 
way to get rid of head lice is to rub a good quantity of a mixture of equal parts 
of kerosene and olive oil into the hair, do the head up in a towel, and let the 
mixture remain for at least six hours. Then wash the hair well in hot soap¬ 
suds. If any eggs survive, they will hatch in a week, and another application 
of the mixture will usually complete the extermination of the lice. 


CHAPTER XX 



FOOD ELEMENTS 

Definition of Food. — Food has two uses; first, to 
become new flesh; and second, to be oxidized and 
supply the body with heat and power. 

Any substance which may become a part of living 
flesh , or may be safely oxidized in the body , is a food. 

Foods are mixtures of protein, fat, sugar, water, and 
minerals. These are the same kinds of substances that 
compose the flesh and bones of the body (p. 30). 

Starch is a food substance which is nearly like sugar, 
and which is changed to sugar after it has been eaten. 
The starch in food may be counted as sugar. Starch 
and sugar are often called carbohy'drates. 

Flesh-forming Food. — The living cells of flesh are 
composed principally of protein mixed with minerals 
and water (p. 31). The body does not make its pro¬ 
tein out of other substances, but it takes bits of pro¬ 
tein from digested food and adds them to the living 
flesh. A grown person doing light work needs about 
three ounces of protein each day in order to form new 
flesh in the place of that which becomes worn out. A 
food which contains a great deal of protein is called 


240 




FOOD ELEMENTS 


241 


a flesh-forming food. Examples of this kind of food 
are lean meat, eggs, and beans. 

Fuel Food. — Most of the heat and power of the 
body comes from the oxidation of the fat and sugar 
which are contained in food. When fat and sugar are 
eaten, they are quickly oxidized, and neither of them 
becomes living flesh. They are like the coal which 
is burned in a boiler, but which cannot become a part 
of the machinery. The amount of fuel food which 
the body needs each day is about twelve ounces, or 
four times the amount of its flesh-forming food. 

Protein is like the iron of which the boiler and ma¬ 
chinery are made. But protein is also a fuel food, for 
worn-out flesh is protein which has been oxidized 
(p. 197). 

A food which contains a great deal of fat, or sugar, 
or starch, is called a heat-producing food, or a fuel food. 
Examples of this kind of food are fat meat, potatoes, 
and grain. But these foods contain some protein, 
and are also flesh-forming foods. 

Water and Minerals. — Water and minerals are 
needed in order to carry on the oxidation and the re¬ 
building of the body, and yet they themselves do not 
become oxidized or changed. They go to every part 
of the body with the other food substances, and help 
4 the flesh to make use of the protein, fat, and sugar. 
Minerals are found in nearly all kinds of food, and 
more salt than is needed is usually added to food, on 
account of its taste. 


OV. GEN. HYG.-16 


242 


FOOD ELEMENTS 


If food does not contain the proper minerals, the 
body is weak and does not grow. Softening and decay 
in teeth are often the result of a lack of minerals in the 
food of babies. 

Vitamins. — The body also needs substances called 
vitamins , in order to grow and be strong. There are 
three principal vitamins: 

1. Vitamin number one (or “A”) is found in milk, 
and in cream and butter, and in leafy vegetables. 
A child who gets too little of this vitamin does not grow 
as fast as it should. Lack of this vitamin is also con¬ 
nected with a disease called rick'ets , in which the bones 
are soft and the joints enlarged. 

2. Vitamin number two (or “B”) is found in grains 
just beneath the outer coats of the kernels. Lack of 
this vitamin results in a nerve disease called beriberi , 
which is often found among people who live mostly 
on polished rice. 

3. Vitamin number three (or “C”) is found in 
fruits and fresh vegetables. Lack of it produces a 
disease called scurvy. 

Every child needs milk, green vegetables or fruit, 
and cereals made from whole grain, every day on ac¬ 
count of their vitamins and minerals. 

Flavorings. — Pepper, vanilla, and other flavorings 
are often added to food in order to give it a pleasant 
taste. When food which has but little taste is eaten, 
the body cannot make the best use of it. The use of 
flavorings is to help the body to digest its food. 




FOOD ELEMENTS 


243 


Taste is also a great help in judging the purity and 
healthfulness of food. If a food has a bad taste, it is 
usually not healthful. 

Waste Substances in Food. — The body cannot 
make use of such things as bones, tough strings of flesh 
or fiber, the seeds and skins of fruit, and the husks of 
grain. All foods contain some of these waste sub¬ 
stances, but they form the greater part of the solids of 
some foods, such as cabbage and turnips. Yet foods 
which contain a large amount of waste substances may 
be useful on account of their taste and their effect on 
digestion (p. 200). 

Alcohol as a Food. — Alcohol cannot become flesh. 
It may be oxidized in the body, and may give off heat, 
and therefore some persons would call it a food. The 
body is not made in such a way that it can oxidize 
alcohol with safety. Using alcohol as a food for the 
body is like using it as fuel in a coal stove. Alcohol 
cannot be safely oxidized in the body, and it is not a 
true food. 

Food Values. — The usefulness of food to the body 
is measured in two ways : 

1. By its flesh-forming value. 

2. By its fuel value. 

Flesh-forming Value. — The flesh-forming or growth- 
producing value of a food depends principally on its 
protein, and in part also on its minerals and vitamins. 

There are many kinds of protein. The body needs 
about eighteen kinds, just as one needs many kinds of 



244 


FOOD ELEMENTS 


lumber in building a house. A food may contain 
some kinds of protein which the body cannot use, or 
it may lack some kinds which the body needs. The 
right kinds and amounts of protein that the body needs 
are found in milk, and therefore milk has a high flesh¬ 
forming value. Next in value are the proteins of eggs 
and meat, then those of cereals, and lastly those of 

vegetables and fruits. 
About one sixth of the 
protein must be of an¬ 
imal origin, such as 
milk, eggs, meat, or fish. 
If the body does not 
get some of these foods, 
it becomes weak, and 
loses weight. 

Protein will not be¬ 
come flesh unless 
minerals and vitamins 
are also present. Green 
vegetables and fruit 
contain very little pro- 
I tein or fuel substances, and yet a person cannot live well 
without them, for they supply minerals and vitamins. 

The growth-producing values of foods are tested 
by means of experiments in feeding white rats, guinea 
pigs, and other lower animals, and by the observations 
of farmers in feeding pigs and other domestic animals. 
These experiments show the food requirements of the 



Effect of Vitamins 

The larger pig is the younger, but it was 
fed some green stuff every day. The smaller 
pig got only grain, which lacks one kind of 
vitamins; but when it was fed green stuff, 
it soon caught up with the other pig in 

size. 











FOOD ELEMENTS 


245 


human body, for the living flesh of lower animals 
grows in the same way as that of man. 

Fuel Value of Food. — The fuel value of food is 
shown by the number of calories of heat which the 
food will produce when it is oxidized (p. 172). The 
fuel foods are fat, sugar, and starch. Protein also 
has a fuel value, for nearly all the protein which is 
built into living flesh takes the place of other protein 
which has been oxidized. 

A man doing 'very light work produces about one 
hundred calories of heat each hour. He produces 
heat about as fast as two burning candles. 

If you know how many calories each kind of food will 
produce, you can reckon how much food you need to 
eat. If an ounce of protein, or sugar, or starch is 
oxidized, it will yield about one hundred and twenty 
calories. An ounce of fat will yield about two hundred 
and forty calories. 

If a man should eat nothing but protein, his body 
would require about twenty ounces a day, or about 
as much as is contained in the whites of nine dozen eggs, 
in order to furnish the 2400 calories that he needs. If 
he should eat nothing but fat, about ten ounces of 
butter would supply the calories that he needs. If 
he should use only sugar for food, he would need about 
one and a quarter pounds each day. But he cannot 
live on either kind of food substance alone. A person 
needs to eat a mixture of protein, fat, and sugar in 
order to be healthy. 



246 


FOOD ELEMENTS 


Amount of Food. — In reckoning how much food 
to eat, first choose enough protein to replace that which 
is worn out and oxidized in the flesh. The amount of 
protein which will be needed is about three ounces a 
day (p. 240). This quantity of protein will produce 
three hundred and sixty calories of heat, which is 
about one sixth as much as the body needs. The re¬ 
maining 2040 calories could be obtained from four 
ounces of fat and nine ounces of starch or sugar, or 
from two ounces of fat and thirteen ounces of starch 
or sugar. A person who does hard work will need 
much more than these amounts of food substances. 

Concentrated Food. — Some persons think that there 
are foods which are so concentrated and nourishing 
that a teaspoonful of them mixed with a glass of water 
will supply the body with as much food substance as 
a full meal of bread and meat. This is not so. About 
a small teacupful of pure, dried protein is needed each 
day in order to rebuild the worn-out flesh, and nothing 
else will take the place of that quantity of protein. 

The most concentrated fuel foods are butter and lard, 
and about a cupful of either one is needed to supply 
the daily needs of the body. Two cupfuls of the purest 
and most concentrated food is the very least that will 
keep a person in good health. 

A tablespoonful of meat extract, or beef tea, or pep¬ 
tonized food, does not contain any more nourishment 
than a tablespoonful of milk. These substances may 
have a value as medicines, but they have very little 


FOOD ELEMENTS 


247 


food value. The nourishment in any food consists in 
its protein, fat, and sugar or starch, and these sub¬ 
stances must be in quantities that are measured by 
cupfuls rather than by spoonfuls. 

Composition of Food. — If you know the composi¬ 
tion of the various foods, you can tell what ones to 
choose in order to supply the needs of the body. Those 
who buy supplies for armies reckon the composition 
of the food so that they can buy the right amounts of 
protein, fat, and sugar to supply the needs of the sol¬ 
diers. Farmers often choose the food for their cattle 
by means of tables of the compositions of different kinds 
of hay and grain. The table on the following page shows 
the composition of common foods. 

Balanced Diet. — A group of foods which supply 
the body with all needful food substances without 
waste is called a balanced diet. A day’s balanced 
diet for a man doing light work will contain minerals 
and vitamins, and the following amounts of other 
food substances: 

Protein, 3 oz., yielding 360 calories. 

Fat, 4 oz., yielding 960 calories. 

Sugar or starch, 9 oz., yielding 1080 calories. 

calories. 

An abundance of minerals and vitamins is found in 
most fresh foods in their natural states; but both are 
often lacking in prepared foods, such as fine, white 
flour, granulated sugar, and rice with polished grains 
such as is usually sold in grocery stores. 



248 


FOOD ELEMENTS 


Foods 

Water 

per 

Cent 

Protein 

per 

Cent 

Fat 

per 

Cent 

Sugar 

and 

Starch 

per 

Cent 

Miner¬ 
als per 
Cent 

Calo¬ 
ries in 
Each 
Pound 

White flour .... 

12.5 

II.O 

1.1 

74-9 

o -5 

1695 

Whole-wheat flour . . 

11.4 

13.8 

1.9 

71.9 

1.0 

1700 

Corn meal. 

11.6 

8.4 

4-7 

74.0 

i -3 

1760 

Oatmeal. 

7-3 

16.1 

7.2 

67-5 

1.9 

1880 

Corn meal mush . . . 

60.7 

5-5 

4.8 

27-5 

i -5 

820 

White bread .... 

29.9 

8.9 

4.1 

56.0 

1.1 

1400 

Rice, boiled .... 

72-5 

2.8 

0.1 

24.4 

0.2 

525 

Dried lima beans . . . 

10.4 

18.1 

i -5 

65-9 

4.1 

1665 

Boiled potatoes . . . 

75-5 

2-5 

0.1 

20.9 

1.0 

455 

Tomatoes, fresh . . . 

94-3 

0.9 

0.4 

3-9 

o -5 

io 5 

Cooked beets . . . 

88.6 

2-3 

0.1 

7-4 

1.6 

190 

Fresh asparagus . . . 

94.0 

1.8 

0.2 

3-3 

0.7 

105 

Green corn, kernels . . 

75-4 

3 -i 

1.1 

19.7 

0.7 

480 

Apples, sliced .... 

84.6 

0.4 

0-5 

14.2 

0.3 

300 

Banana pulp .... 

75-3 

i -3 

0.6 

22.0 

0.8 

470 

Peaches . 

89.4 

0.7 

0.1 

9.4 

0.4 

i 95 

Peanut kernels . . . 

9.2 

25.8 

38.6 

24.4 

2.0 

2440 

Roast beef .... 

48.2 

22.3 

28.2 

0.0 

i -3 

I 5 I ° 

Lean ham, cooked . . 

60.0 

25.0 

10.0 

0.0 

5 -o 

865 

Dried beef .... 

44.8 

39 -o 

5 -o 

0.0 

11.2 

940 

Chicken. 

74.8 

21.5 

2-5 

0.0 

1.2 

500 

Fresh codfish .... 

80.0 

18.5 

o -5 

0.0 

1.0 

375 

Salt codfish .... 

53-5 

21.5 

o -3 

0.0 

24.7 

420 

Cooked bluefish . . . 

68.2 

26.1 

4-5 

0.0 

1.2 

670 

Canned crab meat . . 

80.0 

16.5 

i -5 

0.0 

2.0 

375 

Hen’s eggs .... 

73-7 

14.0 

II.O 

0.0 

1.0 

690 

Oyster meat .... 

88.3 

6.0 

i -3 

3-3 

1.1 

230 

Cow’s milk .... 

87.0 

3-3 

4.0 

5 -o 

0.7 

3 i 5 

Cream cheese .... 

34-2 

25-9 

33-7 

2.4 

3-8 

1840 

Butter. 

11.0 

1.0 

85.0 

0.0 

3 -o 

3285 

Sponge cake .... 

15-3 

6-3 

10.7 

65-9 

1.8 

1795 

Custard pie .... 

62.4 

4.2 

6-3 

26.1 

1.0 

825 


Table Showing the Composition of Common Foods, and the 
Number of Calories Produced by Their Oxidation 




























FOOD ELEMENTS 


249 


If too much protein is eaten, all over three ounces 
a day either will be wasted or will be oxidized as fuel 
food. But protein is not a good fuel food, for its oxi¬ 
dized products are not excreted so easily as those of fat 
and sugar. Eating too much protein is a common 
cause of kidney diseases. 

The fat in a balanced diet will supply somewhat fewer 
calories than the sugar and starch. But since fat yields 
twice as much heat as sugar or starch, the amount of 
fat that is needed is less than half the quantity of the 
sugar and starch. 

Some foods contain a great deal of flesh-forming 
substances, and only small quantities of substances 
that are heat-producing. Examples of these kinds of 
food are lean meat and the whites of eggs. Other foods 
consist mostly of heat-producing substances. Exam¬ 
ples of these kinds of food are potatoes and rice. A 
mixture of meat and potatoes helps to make a balanced 
diet, for each has an abundance of what the other lacks. 

Most vegetable foods contain a great deal of sugar 
or starch, and only a small quantity of protein and 
fat. Most animal foods contain a great deal of pro¬ 
tein and fat, and little or no sugar or starch. A mix¬ 
ture of vegetable and animal foods will usually form a 
better balanced diet than either group alone. 

The Arithmetic of Dieting. — The following examples 
show how we may calculate the value of a food. 

Example 1. How many calories will a pound of 
white bread produce ? 



250 


FOOD ELEMENTS 


From the table on p. 248 we find that bread is 8.9 
per cent protein, 4.1 per cent fat, and 56.0 per cent 
starch. The number of ounces of protein in a pound 
of bread is 16 times 0.089, or I -4 2 ounces. The number 
of calories which the protein will produce is 1.42 times 
120, or 170 calories. 

The number of ounces of fat in a pound of bread is 
16 times 0.041, or 0.65 ounce. The number of calories 
which the fat will produce is 0.65 times 240, or 156 
calories. 

The number of ounces of starch in a pound of bread 
is 16 times 0.56, or 8.96. The number of calories in 
the starch is 8.96 times 120, or 1075 calories. 

The total number of calories in a pound of white 
bread is therefore 170 + 156 +1075, or I 4° I calories. 

In like manner the number of calories given in the 
last column of the table on p. 248 may be calculated 
for each kind of food. The numbers given are approx¬ 
imate, ending in o or 5, according to the custom 
in tables of this kind. 

Example 2. If a person were to live on bread alone, 
how much would he need in a day ? 

We first calculate how much bread he should take 
in order to get three ounces of protein a day. From 
the table on p. 248 we find that about one eleventh 
of bread is protein. In order to get three ounces of 
protein, thirty-three ounces of bread, or about two 
pounds, will be needed. The precise calculation is 
3 -T- 0.089 = 33.7 ounces. 


FOOD ELEMENTS 


25 * 


By looking at the table on p. 248 we find that a 
pound of bread will produce about 1400 calories. Thirty- 
three ounces (2^ pounds), therefore, produce about 
2885 calories, which is slightly more than the body 
needs. If the amount of bread is lessened so as to 
produce 2400 calories, the quantity of protein will be 
lessened to about two and one half ounces, which is 
too little for the daily needs of the body. Bread alone 
is, therefore, not a perfectly balanced diet. 

Example 3. If a person were to live on bread and 
butter, how much would he need in a day? 

If butter is spread rather thin, it will weigh about 
one tenth as much as the bread. The thirty-three 
ounces of bread given in Example 2 will have about 
three and one half ounces of butter on it. From the 
table on p. 248 we find that a pound of butter contains 
very little protein, but it produces 3285 calories. 
Therefore, three and one half ounces of butter will pro¬ 
duce 718 calories. The total number of calories produced 
by the thirty-three ounces of bread and the three an 
one half ounces of butter will be about 3600 calories. 

The proper number of calories, or 2400, will be ob¬ 
tained from two thirds of thirty-three ounces of bread, 
or twenty-two ounces, and two thirds of three and one 
half ounces of butter, or about two and one half ounces. 
But in this quantity of bread and butter, there are only 
two ounces of protein, which are only two thirds as many 
as the body needs. A bread and butter diet is there¬ 
fore not well balanced. 



252 


FOOD ELEMENTS 


Example 4. If a person were to live on ham sand¬ 
wiches, how much of that food would he need in a day? 

From Example 3 we find that thirty-three ounces 
of bread, spread with butter, will contain three ounces 
of protein, and will produce 3600 calories. About half 
a pound of lean boiled ham sliced thin will be used 
in making the bread and butter into sandwiches. From 
the table on p. 248 we can reckon that the ham will 
contain about two ounces of protein, and will pro¬ 
duce about 432 calories. The sandwiches will there¬ 
fore contain five ounces of protein, and will produce 
about 4030 calories. Three fifths of the sandwiches 
will contain three ounces of protein, and will produce 
about 2400 calories. One large loaf of bread (twenty 
ounces), with enough butter and ham to make sand¬ 
wiches, is sufficient food to supply all the calories and 
protein that one person needs in a day ; but some fresh 
fruit and vegetables will also be needed in order to 
supply sufficient vitamins and minerals. 

QUESTIONS 

Give a definition of food. 

What are the uses of food ? 

What are the five useful substances which compose foods? 

What substances does a flesh-forming food contain? 

What substances do heat-producing foods contain? 

What foods contain mineral substances? 

What are vitamins? What foods contain vitamins? 

Name some of the waste substances which are contained in food. 

Of what use may they be? 

Give a reason why alcohol might be called a food. 


FOOD ELEMENTS 


253 


Give some reasons why alcohol is not a true food. 

How much protein does a grown person need to eat each day? 

How is the flesh-forming value of a food indicated? the fuel value? 

What is a calorie? 

How many calories of heat does a person’s food need to produce in 
a day? 

How many calories does an ounce of protein produce? an ounce 
of fat? an ounce of sugar? an ounce of starch? 

Why is a teaspoonful of concentrated food a day not sufficient for 
a man? 

What is a balanced diet f 

What food substance will form a balanced diet? 

Look at the table on p. 248 and reckon what quantities of pota¬ 
toes and fresh codfish will be needed in order to supply a person with 
all the protein and fuel food he requires in a day. 

For the Teacher. — While the subject of food elements is complicated and 
scientific, yet its foundation principles may be readily understood, if they are 
presented simply and logically. Refer to Chapter III and review the com¬ 
position of the body. 

There are four classes of foodstuffs: 

1. Flesh-forming, or those containing much protein. 

2. Fuel, or those containing much starch, sugar, or fat. 

3. Vitamins and minerals. These constitute almost the entire food value 
of greens, salads, and juicy fruits. 

4. Flavorings, which are needed in order to stimulate the processes of 
digestion, for tasteless food is not easily digested. 

There are three common measures of food values: 

1. The protein content of food, or rather its content of the kinds of protein 
which the body can use. 

2. The total calories that the food can yield on oxidation. Refer to Chapter 
XV and review the topic of calories. 

3. The vitamin and mineral contents. These vary widely from practically 
nothing in white flour, to considerable in milk, greens, salads, and juicy fruits. 

A balanced diet is a day’s menu which supplies all kinds of food elements 
in their proper proportions. It can be reckoned by reference to tables of the 
composition of various foods like that on page 248. 

Coordinate this chapter with arithmetic by calculating the calories in 
various foods, such as those in the examples which are given. 


CHAPTER XXI 


DIGESTION 



Changes Produced by Digestion. — The forms of 
protein, fat, and sugar which can enter the blood are 
seldom found in food before it is eaten, but they are 

produced by 
changes which 
take place in food 
after it has been 
swallowed. The 
change of food 
which has been 
eaten to forms 
which can enter 
the blood is called 
digestion (di-jes'- 
chun). 

Cooking. — The 

work of digestion 
is begun outside of the body by cooking , or heating the 
food. Cooking softens and dissolves most foods and 
makes them ready to be digested within the body. 

Starch forms the principal part of cereals and vege¬ 
tables, and is in the form of microscopic grains. The 


Grains of Potato Starch 

(Magnified 300 times.) The starch is in layers 
which are separated by a substance like paper. 
Heat bursts the grains. 


254 




DIGESTION 


255 


starch in each grain is in layers which are separated by 
thin sheets of an indigestible substance like paper. 
When food is cooked, the heat causes the grains to 
swell and burst. The digestive juices can then easily 
reach the starch. 

Much of the protein of meat and vegetables is in a 
tough, hard form which cannot be easily softened by 
the digestive juices. Cooking softens the protein 
and allows the digestive juices to reach every part. 

The fat in nearly all kinds of food is held in tiny 
pockets of protein (p. 32). Cooking softens the 
pockets and sets the fat free. 

Changes Produced by Digestion. — Nearly all 
of our food was once a living part of an animal or 
plant. The protein, fat, sugar, and starch of food are 
complex substances which animals and plants have 
built up from simpler substances. When a man 
digests food, he tears the complex foods to pieces and 
breaks them up into the simpler substances of which 
they are composed. He then uses the simple sub¬ 
stances in building his own blood and flesh. The 
process is like that of tearing down a house and using 
the old boards, bricks, and nails in building a new house. 

The protein of human flesh is composed of about 
eighteen kinds of simple substances, called am'ino 
acids. These and other kinds of amino acids are found 
also in protein food. The digestion of proteins consists 
in tearing these amino acids apart from one another, 
and from other kinds which the body cannot use. 


256 


DIGESTION 


Fats are composed of simpler substances, called 
fatty acids , joined to glycerin. When a fat is boiled 
with soda, the fatty acid leaves the glycerin and unites 
with the soda to form soap. When fat is digested, it 
is broken into a fatty acid and glycerin, and the fatty 
acid unites with soda or potash to form soap. The 
digestion of fat produces soap and glycerin. 

A fat will not dissolve in water, but if the fat is 
shaken with water containing soap, it is broken into 
microscopic drops which float in the water and pro¬ 
duce a white liquid called an emul'sion. Milk is an 
emulsion of butter fat. An emulsion of fat is pro¬ 
duced during digestion. 

Starch and sugar are complex substances which are 
changed by digestion to a simple form called glu'cose, 
or grape sugar. 

Enzymes. —The principal part of the work of diges¬ 
tion is done by means of substances called ferments , 
or enzymes (en'zlmz). An enzyme will produce a contin¬ 
uous change in a substance without losing its own power 
of action or itself becoming changed. An example 
of the work of enzymes is the change of sugar to alcohol 
and carbon dioxide by yeast plants (p. 40). 

Organs of Digestion. — Food is digested in a tube 
which begins at the mouth, and extends the whole 
length of the trunk of the body. The part of the diges¬ 
tive tube just back of the mouth is called the phar'ynx 
(farhngks), and the next part of the tube is called the 
esoph'agus. The pharynx is a muscular box which 



DIGESTION 


257 


squeezes food into the esophagus at the beginning of an 
act of swallowing. The esophagus conducts the food 
into the stomach. 

The stomach is so much larger than the rest of the 
digestive tube that it looks like a bag between the ends 
of two smaller tubes, the esophagus and the intestine 
(m-tes'tin). It is composed of muscle, and holds about 
two quarts. It lies crosswise of the body, mostly on 
the left side between the ribs and the waistline. 

The intestine is the part of the digestive tube which 
is below the stomach. It is a thin, muscular tube, 
somewhat larger than a person’s thumb, and about 
five times as long as his body. It lies in coils and 
nearly fills the lower part of the trunk of the body. 
Another name for the intestine is the bowel. The 
lower fifth of the intestine is two or three times as 
large as the upper four fifths, and is called the large 
intestine. 

Fluids of Digestion. — The body digests food by 
dissolving it in liquids which are produced by glands 
in the mouth, the stomach, and the intestine. 

The liquid in the mouth is called the saliva. It 
contains enzymes which change starch to grape sugar. 
It is produced by six organs called the salivary glands. 
Two of them lie in front of the ears, two under the sides 
of the lower jaw, and two under the front part of the 
tongue. These glands are swollen during the sickness 
called mumps. ^ 

The digestive’" fluid in the stomach is called the 


OV. GEN. HYG.-I 7 



258 


DIGESTION 



gas'trie juice. It contains an enzyme, called pepsin, 
which changes protein to amino acids. It is poured 
out by the lining of the stomach in the same way that 

perspiration is poured out 
by the skin. It is formed 
in thousands of tiny glands 
which stand side by side, 
like pin pricks, in the mucous 
membrane of the stomach. 

The fluids of the intestine 
are the intestinal juice, the 
pancreatic (pang-kre-at'ik) 
juice, and the bile. The 
intestinal juice is produced 
by glands which lie in the 
mucous membrane of the in¬ 
testine, and which are like 
the glands in the stomach. 
The pancreas (pang'kre-as) 

is a large gland which lies behind the stomach. It 

« 

manufactures a liquid, called the pancreatic juice , 
which it sends into the upper part of the intestine 
through a small tube. 

The liver is a large gland which lies under the ribs 
on the right side of the body. It produces a bitter, 
yellow liquid, called the bile , which flows into the in¬ 
testine through the same tube through which the pan¬ 
creatic juice flows. The bile is a waste substance, but 
it assists in the work of digestion. 


Glands of the Stomach 

(Magnified 200 times.) They 
stand closely packed side by side, 
and produce gastric juice, a, 
surface of stomach; b, gland; c, 
connective tissue. 





























DIGESTION 


259 


The work of the mixture of liquids in the intestine 
is to change starch and sugar to grape sugar, and pro¬ 
tein to amino acids, and to make fats into an emulsion 
and change them to soap and glycerin. Thus the 
mouth begins the digestion of starch, the stomach 
begins the digestion of protein, and the intestine di¬ 
gests all kinds of food. 

Time Required for Digestion. —* Digestion begins 
almost as soon as food enters the mouth, and some of 
the food is ready to enter the blood within ten minutes 
after it has been swallowed. The stomach will usually 
be empty in about three hours after eating, but the 
digestion of food will continue for about six hours in 
the upper intestine, and for twelve hours in the large 
intestine. 

Peristalsis. — The greater part of the flesh of the 
esophagus, stomach, and intestine consists of involun¬ 
tary muscle (p. 79). The use of the muscle is to force 
the food down the digestive tube. It contracts in 
ringlike waves which run down the esophagus, stom¬ 
ach, and intestine, and force the food onward, just 
as if each wave were a ring running slowly down the 
digestive tube. This motion is called peristalsis 
(per-i-stal'sis). When food reaches any part of the 
digestive tube, peristalsis begins in that part, and the 
motion of the part usually stops as soon as food has 
passed it. 

The stomach and intestine force the food onward 
with a slow and gentle motion that is not usually felt. 



2 6o 


DIGESTION 


But if the wrong kind of food is eaten, the muscles 
may act rapidly and forcibly in order to push the 
harmful food out of the body. The peristalsis then 
causes the kind of pain which is called stomach ache. 

When a harmful kind of food is swallowed, the waves 
of peristalsis sometimes run backward and force the 
food back into the mouth. This backward motion of 
' food into the mouth is called vomiting. 

Exercise during Digestion. — Digesting food re¬ 
quires the muscles of the stomach and intestine to 
work. If you exercise or study hard near a mealtime, 
you may use up your strength, and may not have 
strength left to digest your food properly. Take a 
few moments for rest after each meal. 

Bacteria in the Intestine. — The intestine contains 
great numbers of living bacteria which are very much 
like the bacteria of decay outside of the body. They 
live upon that part of food which does not become 
digested, and as they grow, they cause the food to 
decay. The food is then as poisonous as it would have 
been if it had been spoiled when it was eaten. Many 
of the bad feelings which are caused by poor digestion 
are due to the decay of undigested food. Getting 
rid of undigested food is an important part of digestion. 

Chewing Food. — No one can control the digestion 
of food in the stomach and intestine, but the way in 
which a food is eaten has a great deal to do with the 
way in which it will be digested. If a food is eaten 
properly, it will usually be digested readily. 


DIGESTION 


261 


Grinding food to small bits in the mouth helps all 
the digestive fluids to dissolve it. A great deal of poor 
digestion comes from swallowing food in lumps which 
are too big for the digestive juices to dissolve easily. 
Chewing food is one of the most important steps in 
digestion, for it breaks the food into small pieces which 
the stomach and intestine can easily digest. 

Mouth Digestion. — Another object of chewing 
food is to mix it with saliva. Each mouthful of food 
does not remain in the mouth long enough for much of 
its starch to be digested there, but the saliva continues 
to act for about half an hour after the food reaches the 
stomach. About half of the work of digesting starch 
may be done by the saliva, if food is eaten slowly. 

The main part of the food usually eaten is starch. 
If starch is not digested by saliva, the intestine has 
to do double work to digest it. The food will then 
not digest well, and it will be the cause of headaches 
and stomach aches. If you chew soft food, such as 
oatmeal, long enough to mix it with saliva, you will 
help the stomach and intestine to digest it. 

Eating Fast. — When you eat fast, you cannot chew 
your food well, or mix it with saliva. The stomach and 
intestine cannot do the work which the mouth should 
have done. If your food is not well digested in the 
4 mouth, a large part of it will escape digestion in the 
stomach and intestine. You will get no more nourish¬ 
ment from a large quantity of food eaten fast, than from 
a small quantity eaten slowly. A little food well 



262 


DIGESTION 


digested is better than a great deal half digested. If 
you have only five minutes for eating, you will get 
about as much nourishment by eating slowly as by 
eating fast. You cannot chew all your food well if 
you take less than fifteen minutes in eating a meal. 

Drinking at Mealtimes. — Some kinds of food, such 
as soup, contain a great deal of water, and other kinds, 
such as crackers, are very dry; yet you can easily 
digest both kinds. Taking water with a meal may 
aid digestion, for it separates the bits of food, and en¬ 
ables the digestive enzymes to reach every part. You 
may safely drink water with a meal, if you are thirsty. 
But drinking water in order to be able to swallow food 
rapidly is harmful to the digestive organs. 

Eating between Meals. — The muscles of the stom¬ 
ach and intestine become tired and need a rest, as the 
muscles of the arm do. The cells of the glands which 
produce the digestive juices also need to rest often. 
It is best to eat only at mealtimes, so that the stomach 
and intestine may have time to rest between meals. 

How Much to Eat. — The feeling of hunger is a nat¬ 
ural guide by which you can tell when to eat, and how 
much food to take. Hunger is usually a safe guide if 
you eat slowly and chew your food well. But your 
hunger and your appetite will often lead you to eat 
wrongly if you eat rapidly or if you take food for the 
sake of its taste, or for the pleasure of eating. If you 
eat slowly and only at mealtimes, you may safely eat 
enough to satisfy your natural hunger and appetite. 



DIGESTION 


263 


The Feelings and Digestion. — Your feelings have 
a great deal to do with the digestion of food. When 
you are hungry, the sight and smell of good food cause 
the saliva to flow into the mouth. If you enjoy the 
taste of food, the gastric juice will begin to flow into 
the stomach as soon as you begin to eat. But if you 
eat when you have no desire for food, or if the food has 
an unpleasant taste, or if you are sad or angry, neither 
the saliva nor the gastric juice will flow properly, and 
your food will not be well digested. 

Politeness and good manners at table are great aids 
to digestion, for they make you happy and help you to 
enjoy your food. Other things which will help you 
to digest your food are good cooking, clean dishes, and 
pleasant conversation. 

Rules for Eating.—Your stomach and intestine 
will usually digest all the food that you need if you eat 
it properly. Most persons who have indigestion have 
brought the sickness on themselves by eating either 
too rapidly, or too much, or too often. Their indiges¬ 
tion will usually stop, and their digestive organs will 
nearly always do their work well again, if they eat 
properly. 

It is not hard to learn to eat properly. The rules of 
good table manners are excellent rules for eating in a 
healthful way. That is, it is good manners to eat 
slowly and not too much, to chew the food well, 
to be cheerful at the table, and to follow all the 
other rules of healthful eating. 


264 


DIGESTION 


QUESTIONS 

What changes does cooking produce in food ? 

What changes does digestion produce in protein? in sugar and 
starch? in fat? 

Describe the stomach; the intestine. 

What is an enzyme ? 

What is the saliva ? 

What changes in food are produced by digestion in the mouth? 

What is the gastric juice? How is it formed? 

What changes does the gastric juice produce in food? 

What fluids digest food in the intestine? 

In what organs is starch digested? protein? fat? 

What is peristalsis? 

How much time is required for mouth digestion? for stomach 
digestion? for digestion in the intestine? 

What effects are produced by bacteria growing in the intestine? 

How does chewing food well assist the stomach and intestine to 
digest food? 

Why is it necessary to chew soft foods, such as oatmeal? 

Give some reasons why you should eat slowly. 

What way of drinking at a mealtime is harmful? 

Why is eating between meals harmful? 

How can you know how much to eat ? 

In what respect are the rules of good table manners also good rules 
for heathful eating? 

For the Teacher. — It is extremely seldom that any plain food will “ dis¬ 
agree ” w r ith any person if it is eaten in the proper way and at the proper time. 
Continually thinking about one’s stomach is likely to produce the discomforts 
which are ascribed to indigestion. 

Emphasize the value of milk, vegetables, and fruit in promoting the appetite 
and digestion. Deficiency in the amount of foods containing vitamins is a 
common cause of a poor appetite. The older books describe peptone as the 
product of digestion of proteins. Advances in knowledge have shown that 
amino acids are the basic substances out of which proteins are built, and that 
about eighteen kinds are yielded by the digestion of the common proteins in 
foods. Peptone is a name given to protein substances in a stage of digestion 
intermediate between proteins and amino acids. 


CHAPTER XXII 


ABSORPTION AND ASSIMILATION 

Absorption of Food. — Digested food is a whit¬ 
ish liquid which looks like thin cream. It is mixed 
with the indigestible parts of the food and with many 
waste matters of the body. It is of no use to the body 
until after it has passed into the blood. The passing of 
digested food into the blood is called absorption. 

A large quantity of blood flows through a network 
of capillaries which lie very near the surface of the 
mucous membrane of the intestine. All that separates 
the food from the blood is a thin partition composed 
of a single layer of epithelial cells and the thin walls of 
the capillaries. This partition is as thin as tissue pa¬ 
per, and allows water, minerals, and digested protein 
and sugar to pass through it readily and enter the 
blood stream. 

Osmosis. — The mingling of unlike liquids and gases 
which are separated by a thin partition through which 
they can pass is called osmo'sis. The absorption of di¬ 
gested food into the blood is an example of osmosis. 
The following experiment will illustrate the process: 

Carefully remove some of the shell from the large 

265 


266 ABSORPTION AND ASSIMILATION 

end of an egg, taking care not to break the thin mem¬ 
brane which lines the shell. Set the broken end of 
the egg into a small glass of water, and make a small 
hole through both the shell and the lining in the upper 

end. A large amount 
of water will pass into 
the egg, and will cause 
the white of the egg to 
overflow through the 
upper hole within fifteen 
minutes. The force 
which causes water to 
flow through the mem¬ 
brane and into the egg 
is that of osmosis. A 
small quantity of sub¬ 
stance from the egg 
will also pass into the 
water, but it will be 
much less than the 
amount of water which 
passes into the egg. 

Osmosis in the In¬ 
testine. — The epithe- 
the walls of the capil¬ 
laries form a thin membrane which is like the lining 
of the eggshell. The force which causes digested food 
to pass through the membrane into the blood is that of 



An Experiment in Osmosis 


The white of the egg is separated from the 
water by the lining of the eggshell. Water 
passes through the lining and fills the egg 
so full that some of its white overflows 
through the hole in the top of the egg. 

Hal cells of the intestine and 


osmosis. 





ABSORPTION AND ASSIMILATION 


267 


Other Examples of Osmosis. — The exchange of 
oxygen and carbon dioxide in the air sacs of the lungs, 
and that of oxygen and waste substances between the 
capillaries and the cells of the body, are examples of 
osmosis. 

Changes in Absorbed Food. — The epithelial cells 
of the lining of the intestine begin the work of rebuild¬ 
ing protein and fat out of the simple forms which were 
produced by digestion. The cells combine the amino 
acids and make them into the proteins which are found 
in the blood. They tear apart the soap which was pro¬ 
duced by digestion, and rebuild it into fat. The glu¬ 
cose, minerals, and water are not changed as they pass 
through the ef&thelial cells. 

The Liver. — The blood stream which leaves the 
intestine carries the absorbed protein and sugar to the 
liver. The cells of the liver change some of the sugar 
to a form called gly'cogen , and store it for use between 
meals. The liver cells also remove harmful sub¬ 
stances which may have been absorbed, and send them, 
with the bile, back to the intestine. 

Absorption of Fat. — The cells of the epithelium of 
the intestine do not pass the absorbed fat into the cap¬ 
illaries, but into lymph tubes, called lacteals (lak'te- 
alz). The lacteals unite in a large tube called the 
thoracic (tho-ras'ik) duct , which conducts the digested 
fat into a large vein near the heart. 

Villi. —- The mucous membrane of the intestine is 
covered with tiny projections, called vil'li, which look 


268 


ABSORPTION AND ASSIMILATION 


like the short threads on velvet. Each villus con¬ 
tains a lacteal and a great number of capillaries. The 

villi are like tiny roots. They 
extend into the liquid food and 
take it up quickly. 

What the Body Does with 
Food. — Putting digested food 
to use throughout the body is 
called assimilation. The blood 
carries a stream of digested food 
to every living part. Flesh that 
has lost some of its substance 
by oxidation takes up protein, 
minerals, and water, and repairs 
itself with them. Glands take 
what they need in order to 
..... , form their juices. Muscles take 

o, villus; b, inner surface J 

of the intestine; c, glands up sugar and fat, and oxidize 

in the mucous membrane. 

them to produce heat and power. 
Each part of the body takes the substances which 
it needs. 

Undigested Food. — The parts of food which are not 
digested are slowly forced along the intestine, and are 
finally expelled from it. The intestine also expels the 
bile and other excretions which the liver has taken 
from the blood. Expelling waste matters and undi¬ 
gested food is the last act of digestion, and is as im¬ 
portant to health as eating. 

Some foods, such as vegetables and brown bread, 



Villi and Intestinal 
Glands 





ABSORPTION AND ASSIMILATION 


269 


contain strings and fibers which are like wood, and 
which do not become digested or decayed in the in¬ 
testine. Harmless indigestible substances like these 
are necessary for health, for they help the peristalsis 
of the intestine. 

Overeating. — The cells of the body will not use 
more food than they need, even though the blood 
brings a large quantity of food to them. Overeating 
may cause the body to store up great quantities of 
fat, but the fat is a weight which is often a burden 
instead of a help. 

The cells of the body cannot use more fuel food than 
they can oxidize. If a person sits still, or does very 
light work, he takes only a small quantity of oxygen 
into his body, and oxidizes only a small amount of 
food. If the blood takes up more food than the body 
can oxidize, some of the food will be half oxidized. 
The excretions will then be poisonous, and will cause 
headaches, rheumatic pains, and kidney diseases. 
One of the principal causes of these forms of sickness 
is overeating. If you suffer from the effects of over¬ 
eating, the cure is either to eat only a little food for 
a few days, or to take a great deal of exercise, in order 
to oxidize the extra food in your blood. 

Growing Fat. — Thin persons often try to grow fat 
by eating all that they can. This will not always 
make them fat, for the food may not be digested, and 
the cells of the body may not make use of that which 
has been digested. But many persons gain flesh when 



2JO 


ABSORPTION AND ASSIMILATION 


they eat less food than usual, and eat it properly, for 
the food may then be well digested, and the cells may 
get the right kinds and amounts of food that they need. 

Growing Thin. — A stout person can get rid of his 

fat by eating so 
little food that his 
body has to oxidize 
its fat. In order 
to get rid of ten 
pounds of fat in a 
month, a person 
must oxidize about 
five ounces of fat 
each day. Five 
ounces of fat will 
produce 1200 cal¬ 
ories of heat, or 
about half the heat 
which a man’s daily food produces (p. 247). If a 
person eats only half as much food as he requires, 
his body will oxidize its fat, and he will become thin. 

Another way of getting rid of the fat in the body 
is to take a great deal of hard exercise in order to com¬ 
pel the body to oxidize its fat. 

Poor Nourishment. — Young persons who are 
healthy and strong will grow constantly and regularly. 
Tables of standard heights and weights have been 
made for each year of their age. A child whose height 
and weight are less than the standard for his age is said 



Weighing and Measuring Children at 
School 










ABSORPTION AND ASSIMILATION 


271 


to be poorly nourished. Children are regularly meas¬ 
ured and weighed in many schools, and those who are 
poorly nourished are taught how they may grow to 
the proper size and strength. 

The following table shows the height and weight of 
an average healthy American child at each year of its 
age: 

BOYS GIRLS 


Age 

Height 

Weight 

Height 

Weight 

Inches 

Pounds 

Inches 

Pounds 

I 

29 

21 

28.5 

19-5 

2 

33-5 

26.5 

33 

25 

3 

36.5 

30-5 

36 

29-5 

4 

39 

34 

38.5 

33 

5 

41-5 

38 

4i 

37 

6 

44 

4i 

43-5 

40 

7 

45-5 

49 

45-5 

47 

8 

47-5 

54 

47-5 

52 

9 

49-5 

59 

49 

57 

10 

5i-5 

65 

5i 

62 

11 

53 

70 

53 

68 

12 

55 

77 

56 

78 

13 

57 

85 

58 

89 

14 

60 

95 

60 

98 

i5 

62 

107 

61 

106 

16 

65 

121 

61.5 

112 


There are three principal causes of poor nourishment: 

1. Diseases and defects of the body. 

2. Overwork or lack of rest. 

3. Wrong food or wrong habits of eating. 
Common diseases and defects which prevent growth 

are enlarged glands of the neck, tuberculosis, decayed 
teeth, adenoids, and tonsils which are diseased. An 
examination of a child will show whether or not any of 


272 


ABSORPTION AND ASSIMILATION 


these conditions are present. If they are, they usually 
must be corrected before a child will grow. 

Too much activity and too little rest will prevent 
growth by causing food to be oxidized as fast as it is 
taken into the body. Common acts which prevent 
growth are sitting up late, attending parties and mov¬ 
ing picture shows at night, going on visits often, and 
trying to act as grown people do. It is natural and 
healthful to work and play hard during the day and to 
be tired at night; but long hours of sleep are needed 
in order that the body may rebuild its worn parts. 
A child may need to take a nap after the noon lunch 
in order to gain weight. 

Poor nourishment may be the result of wrong habits 
of eating (p. 261), or the wrong choice of food (p. 247). 
A person who lacks a necessary food element has little 
appetite for any kind of food. Children who do not 
eat green vegetables, fresh milk, and fruit often 
have no appetite because they lack vitamins; and 
yet they may eat candy, cake, and ice cream be¬ 
cause they like the taste of sweets. Forcing chil¬ 
dren to eat does not cause them to grow, for the 
body will not use the food unless vitamins are 
present. The best way to make the appetite return 
is to allow the child nothing to eat except the proper 
food. The child may skip a meal or two ; but when he 
begins to take vegetables, fruit, and milk, the vitamins 
will cause the appetite to return, and the child will 
eat the proper food and will grow naturally. 


ABSORPTION AND ASSIMILATION 


273 


Metabolism. — Two opposing actions are constantly 
taking place in the body : 

1. Upbuilding, or taking food into the body and 
making it into living flesh. 

2. Destruction, or oxidizing food and flesh and ex¬ 
creting the oxidized products. 

The processes of upbuilding and destruction in the 
living body are called metab'olism. The body of a 
healthy grown person carries on its metabolism per¬ 
fectly and smoothly. The substances taken into his 
body exactly balance those excreted; the weight and 
appearance of his body remain the same from day to 
day; and the amount of heat and power developed is 
exactly the amount which the excretions show could 
be developed from the food and flesh which were oxi¬ 
dized. The processes of eating, growth, oxidation, 
heat, work, and excretion are all related closely and 
exactly, and each may be an indicator of the extent 
and perfection of the other processes. For example, 
a physician collects the expired breath of a sick person 
and tests its amount of carbon dioxide in order to es¬ 
timate the rate of oxidation and the amount of food 
which the body requires. 

Thyroid Gland. — Metabolism is largely under the 
control of certain glands in the body. One of these is 
the thy'void gland, which lies in the neck in front of 
the trachea. It is sometimes enlarged and diseased 
and produces a swelling called a goi'ter. The substance 
which it forms has a great effect on metabolism,, 

OV. GEN. HYG. -18 



274 


ABSORPTION AND ASSIMILATION 


especially on oxidation. If the substance is increased 
in amount, oxidation goes on rapidly and the body 
loses weight. If the substance is lacking, oxidation 
takes place slowly, the body increases in weight and 
becomes fat, and the person is dull and lazy. If a 
person who lacks the thyroid substance is given the 
thyroid of a sheep or other lower animal, his metabo¬ 
lism may become normal. 

The effect of the thyroid gland on growth may be 
shown by experiments on tadpoles. If tadpoles are 
fed with small amounts of thyroid gland, they develop 
legs and change to the form of frogs and toads rapidly 
and while they are young and small. If the thyroid 
glands are taken out from the bodies of the young tad¬ 
poles, the tadpoles will continue to grow for years 
until they become large in size, and yet they will not 
produce legs or turn into fully-formed frogs and toads. 

The growth and development of a child depend largely 
upon the thyroid and other glands. Children are 
sometimes dwarfed in both body and mind because 
they lack the proper gland substance. 

QUESTIONS 

What is absorption? 

What are villi? 

What changes occur as digested food passes into the blood? 

What is osmosis? 

How can you illustrate the process of osmosis? 

What does the liver do to food after it is absorbed? 

Describe the absorption of fat. 

Where is fat taken after it is absorbed? 


ABSORPTION AND ASSIMILATION 


275 


What is assimilation? 

What does the body do with food after it is absorbed? 

What are some of the bad effects of overeating ? 

How can a thin person become fat ? 

How can a fat person become thin ? 

Why is some food which cannot be digested necessary for health ? 

What are the three principal causes of poor nourishment ? 

What are some common defects which cause poor nourishment ? 

How does too much activity cause poor nourishment ? 

What effect has the proper choice of food upon the appetite? 

What is metabolism f How may the excretion of carbon dioxide 
indicate the perfection of the process of metabolism in the body? 

What effect does the thyroid gland have on metabolism ? 

For the Teacher. — This chapter deals with nutrition, or the uses to which 
food is put in the body. Emphasize the fact that growing stout or thin depends 
on the balance between eating and oxidation. 

The subject of metabolism comes naturally at this place. The inter¬ 
relation of the processes of eating, growth, oxidation, heat, work, and excretion 
may be mentioned. The effect of the thyroid gland and its extract on metabo¬ 
lism may also be stated. 

The subject of poor nourishment is of great importance in dealing with 
children. A child that is feen per cent under weight for the average child of 
its age is considered to be poorly nourished. 

Emphasize the three great causes of poor nourishment. Diseases and lack 
of rest are of equal importance with improper food in leading to under nourish¬ 
ment, and must be corrected before the child will grow. 

One of the most common defects of diet is the lack of the vitamins which 
are found in milk and green vegetables. A child that drinks a quart of milk 
and eats some green vegetables, or salads, or fruit every day will take all the 
vitamins that are needed, and the child may then take whatever plain food 
is at hand. If vitamins are not taken, the child will have no appetite for food; 
but if food containing vitamins is eaten, the child will have an appetite for 
all kinds of plain food. Vitamins have an effect like that which old-fashioned 
“ tonics ” were supposed to have. Foods rich in vitamins have the same 
“ tonic ” effect on grown persons as they have on children. 

Lean meat lacks the vitamins which produce growth, but these vitamins 
are found in glands such as the liver and kidneys. The value of cod-liver oil 
as a preventive of rickets consists in the vitamins which come from the fish 
livers. A cat fed on beefsteak alone will suffer from poor nutrition; but it 
will thrive on mice because it then obtains the vitamins which are found in 
the glands. 


CHAPTER XXIII 


FOODSTUFFS 

Cost of Food. — A simple way of supplying ourselves 
with food would be to go to a market and buy pure 
protein, fat, sugar, and starch, and then mix them in 
the proper quantities. But no one does this, for the 
mixtures which are made from the pure elements are 
nearly always tasteless and unwholesome. The hu¬ 
man digestive organs are suited to those mixtures of 
food elements in the forms in which they grow natu¬ 
rally in plants and animals. 

The valuable parts of a food are the protein, fat, 
sugar, starch, minerals, and vitamins that are in them. 
Sugar and starch may be bought for about eight cents 
a pound, and fat for about fifteen cents a pound. The 
cheapest protein costs about thirty cents a pound. If 
a food costs more than these prices, the extra price is 
for its taste and appearance, and not for its flesh-forming 
or fuel value. The vitamins and minerals are as 
abundant in cheap foods as in the more costly ones. 
Fruits out of season are costly luxuries. The grains 
have the greatest food value of all foods, and yet they 
cost the least. They are also foods which a person can 
eat day after day without tiring of them. 

276 


FOODSTUFFS 


277 


The following table shows the cost of various foods 
each of which will contain three ounces of protein : 

Oatmeal, i-J- lb. at 5 cents.$0.06 

Beans, 1 lb. at 10 cents .0.10 

Corn meal, 2 \ lb. at 5 cents.o.n 

Potatoes, 8 lb. at 2 cents.0.16 

White bread, 2 lb. at 8 cents.0.16 

Beef, dried, ^ lb..at 40 cents.0.20 

Cheese, lb. at 40 cents.0.30 

Fresh codfish, 1 lb. at 30 cents.0.30 

Beef, round, 1 lb. at 30 cents.0.30 

Hen’s eggs, 1 doz. at 40 cents .0.40 

Cow’s milk, 3 quarts at 16 cents.0.48 

Chicken meat, 1 lb. at 50 cents.0.50 

Beets, 10 lb. at 5 cents.„.0.50 

Oysters, 3 pints at 40 cents.1.20 

Bananas, 5 doz. at 40 cents.2.00 

Apples, 40 lb. at 10 cents.4.00 

The following table shows the cost of various foods, 
each of which will produce about 2400 calories of heat: 

Oatmeal, i-J lb. at 5 cents.$0.06 

Corn meal, i^- lb. at 5 cents.0.08 

Potatoes, 5 lb. at 2 cents.0.10 

White bread, if- lb. at 8 cents.0.14 

Beans, i-g- lb. at 10 cents.0.15 

Beef, round, i-g- lb. at 30 cents.0.45 

Cheese, i^- lb. at 40 cents.0.50 

Milk, 4 quarts at 16 cents.0.64 

Beets, 13 lb. at 5 cents.0.65 

Apples, 8 lb. at 10 cents.0.80 

Eggs, 2 doz. at 40 cents .0.80 

Bananas, 2 doz. at 40 cents.0.80 

Beef, dried, 2 \ lb. at 40 cents .1.00 

Fresh codfish, 7 lb. at 30 cents.2.10 

Chicken meat, 5 lb. at 50 cents.2.50 

Oysters, 10 pints at 40 cents.4-°° 


































278 


FOODSTUFFS 


Food Groups. — The foods in grocery stores, butcher 
shops, and other markets may be divided into four 
groups, as follows: 

1. Animal foods. 

2. Cereals and sugar. 

3. Fleshy vegetables. 

4. Leafy vegetables and fruit. 


r j ■ 



.JkiniS 





T 1 1# i ** A 



1. Animal foods 

2. Cereals and sugar 

* 






3. Fleshy vegetables 

4. Leafy vegetables and fruit 


The Four Food Groups 

In the course of a day, eat at least one food from each group. Be sure to choose 

milk every day. 


Cereals. — The different kinds of grain and the foods 
made from them are called cereals. There are no 
great differences in the composition and digestibility 
of the different kinds of grain. All the cereals contain 












FOODSTUFFS 


279 


protein and a great deal of starch. The only cereals 
which contain much fat are oats and corn. 

Bread, oatmeal, and other foods made from grain 
are the most useful and important of all foods. A 
person could live on them if some leafy vegetables or 
fruits were added in order to supply vitamins. Cereals 
and milk make a well-balanced diet. 

Cereals are the cheapest of all foods. About ten 
cents’ worth of corn meal will 
supply all the protein and 
all the calories that a man 
needs in a day. 

Value of White Flour. — 

White flour is made by sifting 
out the white central parts 
of the ground kernels from the 
coarser, outer parts and the 
indigestible skins or bran. 

Most of the vitamins and 
minerals of grain are in the 
outer parts of the kernels, and 
so they are lacking in white flour. But white flour 
contains an abundance of protein and starch in forms 
which the body can readily use. 

Bread. — Bread, biscuit, crackers, and plain cake 
are nearly alike in composition and digestibility. All 
these foods are full of bubbles, and are said to be light. 
The bubbles are made by carbon dioxide, which is 
formed when yeast or baking powder is added to wet 








28 o 


FOODSTUFFS 


flour (p. 40). When the wet flour is baked, it hardens 
in the form of thin-walled bubbles, which may easily 
be chewed. Wheat flour may readily be made into 
light bread, for its protein becomes sticky when it is 
wet. The protein of corn meal does not become sticky, 
and so corn meal cannot be made into light bread un¬ 
less it is mixed with wheat flour or eggs. 

Fleshy Vegetables. — The principal fleshy vegeta¬ 
bles are beans, peas, potatoes, sweet potatoes, and 
green corn. These contain a large amount of protein 
and can yield a large number of calories. Examples 
of vegetables having a smaller food value are beets, 
turnips, squash, and eggplant. 

Beans and Peas. — Dried beans and peas are rich 
in protein and starch, but some of the protein is in 
a form which the body cannot use. They contain 
very little fat. They are not suited to persons who 
have weak stomachs, but they are excellent foods 
for hardy men who work out of doors, for in such 
persons the stomach usually grows strong with the 
muscles. 

Peanuts and Nuts. —Peanuts are a kind of pea with 
hard pods like thin nutshells. They are like peas in 
composition, except that they have fat in the place of 
about half of the starch of peas. They cannot be 
digested easily, and if they are eaten between meals, 
they are as harmful as beans would be. 

Most nuts are like peanuts in composition, digesti¬ 
bility, and food value. 


FOODSTUFFS 


281 


Potatoes. — Potatoes and sweet potatoes are about 
three fourths water, one fortieth protein, and one fifth 
starch. They contain hardly any fat, but if they are 
cooked with meat, as in a stew, the mixture becomes 
a well-balanced diet. When potatoes are dried, they 
have about the same food value as the least nourishing 
of the grains. 

Garden Vegetables. — The leafy and juicy vege¬ 
tables, such as onions, cabbage, celery, and tomatoes, are 
mostly water, and contain very little protein, starch, 
or sugar, and hardly any fat. They have very little 
flesh-forming or fuel value. Yet if a person does not 
eat them at all, he becomes weak and sick, for they 
are the sources of vitamins and minerals. 

Crews of ships on long voyages used to suffer with 
a disease called scurvy , in which the mouth and skin 
became tender and sore. The disease was caused 
principally by a lack of the vitamins that are found in 
fresh vegetables and fruit. The fully developed disease 
is now rare, for fresh vegetables and fruit are carried 
in a canned or preserved form. But milder results of 
an insufficient amount of fresh vegetables and fruit are 
often seen. The lack of energy that is sometimes 
supposed to be laziness, and the condition that is 
called growing pains , often disappear when the proper 
amount of fresh vegetables and fruit is eaten. 

Fruit. — Dates, bananas, and grapes each contain 
a considerable amount of protein and a large amount 
of sugar. Almost the only food substance in berries, 



282 


FOODSTUFFS 


apples, oranges, peaches, and most other juicy fruits is 
sugar. The skin and seeds of fruits cannot be digested 
at all, and the soft pulp cannot be digested so easily 
as cereal food. Most fruits have about the same food 
value as garden vegetables, and they can take the place 
of vegetables in a diet, for they contain vitamins and 
minerals. They are more expensive than vegetables, 
and are far more expensive than cereals. Dried fruits 
usually contain all the food substances that are found 
in fresh fruits except that the vitamins may be lacking. 

Animal Foods. — Foods which come from animals, 
such as meat, eggs and milk, differ from vegetable 
foods in the following ways : 

1. Nearly all vegetable foods are rich in sugar and 
starch. Few animal foods have any sugar or starch. 

2. Vegetable foods usually contain but little fat. 
Animal foods usually contain much fat. 

3. The fat of vegetables is usually hard to digest. 
Animal fats may be digested easily. 

4. Animal protein is more nearly like the protein of 
human flesh than is the protein of vegetables; and so 
animal protein may be digested and built into human 
flesh more easily than the protein of vegetables. 

A grown person could live on vegetable food, but 
most persons will be helped by eating some protein 
that comes from animal food. The young of human 
beings, higher animals, and birds all must have protein 
of animal origin in order to make good growth. Young 
animals get the protein from milk, and young birds 



FOODSTUFFS 283 * 

get it from worms and insects. The best form of pro¬ 
tein for children is that in milk. 

A danger in the use of animal food is that more than 
the required three ounces of protein will be taken, and 
the kidneys will be overworked in getting rid of its 
oxidized products. Since most animal foods are rich 
in protein, a small amount will supply all that the body 
needs. The foods themselves are usually healthful, 
and are harmful only when an excess is taken. 

Meat. — The flesh of animals is called meat , but 
the word meat usually means the flesh of beef cattle, 
pigs, sheep, and chickens. Lean meat is about one fifth 
protein. Some kinds of meat contain a great deal of 
fat, and other kinds have very little fat, but no meat 
contains much sugar or starch. The different kinds of 
meat, such as beef, pork, and chicken, do not differ 
greatly in composition, or ease of digestion, but there 
are great differences in their cost. 

Some persons suppose that the expensive kinds of 
beef, such as sirloin steak, are more nourishing and 
may be digested more easily than the cheapest kinds, 
such as meat from the neck of an animal. This is not 
so. There is very little difference in the food values 
of the various kinds of beef. The principal difference 
is in the toughness and taste of the meat, but a good 
cook can make tough meat as tender and as tasty as 
the dearer kinds of meat. 

Fish. — The meat of fish is almost like the meat of 
cattle in composition and food value, except that it 



284 


FOODSTUFFS 


usually contains more water, and is less easy to digest. 
It differs from beef principally in its taste. If fish 
is well cooked, it may take the place of meat. Protein 
in the cheaper kinds of fish is almost as cheap as it is 
in cereals. Dried codfish is one of the cheapest of all 
the flesh-forming foods. 

Shellfish. — Oysters, clams, lobsters, crabs, and other 
shellfish are like fish and meat, except that they usually 
contain a little sugar, and a great deal of water. The 
food substances in them are about three times more 
expensive than in meat. 

Shellfish are usually taken from the bottom of bays 
and creeks. If sewage empties into the water near 
them, they are likely to carry disease germs on their 
shells and in their digestive tubes. But if the shell¬ 
fish are well cooked, the disease germs in them will 
be killed. 

Eggs. — Eggs have about the same composition 
and food value as meat. They may usually be di¬ 
gested readily, whether they are raw or are cooked in 
any tasty way. Their ease of digestion depends prin¬ 
cipally on the size of the lumps which are swallowed. 
A raw egg may form a large mass which the digestive 
juices cannot readily enter. A hard-boiled egg may be 
quickly digested if it is chewed to small bits. 

Milk. — Cow’s milk is a complete and well-balanced 
food, for it contains protein, fat, sugar, and minerals 
in nearly the quantities that the body needs. One 
eighth of it is solid substance, and a cup of it contains 



FOODSTUFFS 


285 


more solid food than a cup of oysters. A person doing 
light work would need no more food than four quarts 
of milk a day. It contains rather more protein than 
a grown person needs, but it is the best of all foods for 
young children, for they need a great deal of protein 
in forming new flesh while they grow in size. Milk 
is usually as cheap a food as cheap meat. 

Milk may be digested readily, and it contains hardly 
any indigestible substances. It is one of the most 
valuable of all foods for persons who are sick or have 
weak stomachs. 

Some persons often drink milk instead of water when 
they are thirsty, and are not in need of food. Milk is 
a food as well as a drink; Taking it between meals 
or after a meal is as harmful as taking any other food 
when the body has no need of it. 

Foods Made from Milk. — The fat of milk is in tiny 
drops which float through its liquid and make it appear 
white. When the milk stands quietly for a few hours, 
the fat rises to the surface and forms a layer called 
cream. After the cream has been removed, the milk 
that is left is called skim milk. 

Milk which contains a great deal of cream is called 
rich milk; if it contains a small quantity of cream it is 
called thin milk. Many persons suppose that thin 
milk and skim milk are of little value as food. Thin 
milk and skim milk each contain about as much pro¬ 
tein and sugar as rich milk. Taking the cream from 
milk does not spoil it for food, for nearly all the protein 


286 


FOODSTUFFS 


and sugar are left in the skim milk. The price of 
skim milk is only about half that of whole milk, but it 
has much more than half the food value of whole milk. 

Cream is about one fifth fat, and contains about as 
much protein and sugar as milk itself. When it is 
shaken or stirred, its fat collects into a solid lump called 
butter. The liquid that is left is called buttermilk , and 
has about the same food value as skim milk. 

Cheese. — The protein of milk becomes solid when 
the milk is mixed with a substance, called rennet , which 
contains the digestive juice of a calf’s stomach. When 
the solid protein is pressed into a mass it is called 
cheese. Most cheese also contains a large quantity 
of fat. The flavor of cheese is caused by bacteria 
which grow either in the milk, or in the cheese after 
it has stood for a few days or weeks. Cheese is one of 
the most nourishing of all foods, and usually it may 
be digested easily. 

Vitamins in Milk. — Milk is one of the best of all 
sources of the vitamins which cause growth. Every 
child needs milk every day ; but as a child grows older, 
it can obtain the vitamins from green vegetables and 
salads. The vitamins in cow’s milk come from the 
grass which the animal eats. Men can get the same 
vitamins from green vegetables. 

Tea and Coffee. — Tea and coffee are two drinks 
which most persons have on their tables. Tea is made 
from the dried leaves of the tea plant, and coffee is made 
from the roasted berries of the coffee shrub. They each 


FOODSTUFFS 


287 


contain a substance, called caffeine (kaf'e-m), which 
keeps a person awake, and rouses his mind to work. 
Tea and coffee are stimulants, and do not supply the 
body with any food substance. The drinks are of 
value to grown persons who have to do hard work. 
They also have a great value in some forms of sickness, 
but they do more harm than good to children. If 
you cannot work or keep awake without them, there is 
something the matter with you, and neither of the 
drinks will be of any real help to you. 

Cocoa. — Cocoa and chocolate are drinks which are 
made from the roasted seeds of the cacao tree. They 
each contain a substance which is like caffeine, but 
is somewhat weaker. For this reason children can 
usually drink cocoa and chocolate more safely than 
tea or coffee. 

Choice of Food. — When you buy food for a meal, 
choose the things that will make a well-balanced diet. 
You can do this by taking something from each of the 
four food groups that are mentioned on page 278. 

A good bill of fare for a day could be as follows : 


Breakfast 


Lunch 


Dinner 


Apples 

Cream of wheat 

Sausage 

Toast 

Butter 

Milk 


Vegetable soup 

Saltines 

Scalloped corn 

Green onions 

Banana and nut salad 

Bread 

Butter 

Milk 


Boiled ham 

Baked potatoes 

Milk gravy 

Creamed lima beans 

Pineapple sauce 

Celery 

Bread 

Butter 

Milk 


288 


FOODSTUFFS 


These foods contain protein, sugar, starch, fat, 
minerals, and vitamins, and are foods which you will 
enjoy eating. It is necessary that those who supply 
food for institutions, or for the army and navy, should 
choose those which contain all the food substances 
that the body needs. 


QUESTIONS 

What is the least cost of a pound of sugar? of starch? of fat? of 
protein ? 

Name the principal food groups. 

What are cereals? 

What food elements do cereal foods contain? 

What is light bread ? 

Why cannot corn meal alone be made into light bread? 

What food elements does white flour lack ? 

What food substances do fleshy vegetables contain? 

For what class of persons are beans well suited? 

What is the food value of peanuts? 

What food substances are contained in potatoes? 

Why does a person need to eat garden vegetables ? 

How may scurvy be prevented? 

What food substances does fruit contain? 

How do dried fruits compare with the fresh fruits in food value? 
Compare animal foods with vegetable foods. 

What food substances are found in meat ? 

What is the principal difference between the expensive kinds of 
meat and the cheaper kinds? 

What food value has beef tea? 

How does fish compare with meat in food value? 

What is the difference in food value between shellfish and meat? 
What food substances are found in eggs? 

What food substances are found in milk? 

Why is milk one of the most valuable of all foods for children? 


FOODSTUFFS 289 

How much milk would a man doing hard work need to drink if he 
took no other food? 

What is the food value of cream? of skim milk? of buttermilk? 
of butter? 

Of what food elements does cheese consist ? 

Why are coffee and tea called stimulants, and not foods? 

What substance in tea and coffee is a stimulant ? 

Why is cocoa a better drink for children than tea and coffee? 

Write out a day’s bill of fare (different from the one in this book) 
which contains all the food elements that the body needs. 

For the Teacher. — The topics in this chapter lead up to the practical one 
of choosing menus. It is practical and scientific to divide foods into the four 
groups which are mentioned in the text. A menu is likely to afford a balanced 
diet if in the course of a day it contains a food from each group. 

Experiments on lower animals and experience in feeding children show that the 
food substances which are lacking the most often are the vitamins and minerals that 
are found in milk, fresh vegetables, and fruit. Under the conditions which exist 
in most American homes a practical rule is to eat the following substances in the 
course of a day : 

1. Milk, either alone or in cooked dishes, one quart daily. 

2. Raw fruit, or salads, or greens; a goodly helping in at least one meal each day. 

3. Any other foods that satisfy the taste and appetite. 

Have the pupils write out the names and amounts of the food which they 
ate for a certain day. Discuss the menus from the standpoint of balanced 
diets. 

The question of vegetarianism is often brought up. It is possible for adults 
to live healthy, vigorous lives when they eat no animal food, but it is doubtful 
if children can do so. Most so-called vegetarians use milk, which is an 
animal food, and many use eggs also. It is true that most Americans eat 
much more meat than they need. 

The cost of food is not a true indication of its food value, as is shown by the 
tables on page 277. Cereals bought ready for the table cost at least five times 
as much as oatmeal, but are no more nourishing. Desserts are far more costly 
than their constituent food substances would be if they were plainly cooked. 


OV. GEN. HYG. — 19 


CHAPTER XXIV 


WHOLESOME FOOD 

Storing Food. — Fruit, meat, and many other foods 
which naturally decay within a few days may be pre¬ 
served for a long time if proper care is taken to prevent 
bacteria and molds from growing in them. Three 
ways of preserving foods in large quantities are by 
canning them, by drying them, and by putting them 
in cold storage. 

Canned Foods. — Cooked foods will remain fresh 
for years if they are properly canned, for they are then 
protected from bacteria and molds (p. 43). If food 
is fresh, and is properly canned, it will retain its ap¬ 
pearance and wholesomeness for years without the 
addition of preservatives. 

Drying Food. — Fruits, vegetables, and meat will 
remain free from bacteria and molds, and will keep 
fresh, if they are dried and are then stored in a dry 
place. Food that has been properly dried and stored 
has almost the same food value that it had while it was 
fresh, except that the amount of vitamins is some¬ 
times lessened. Dried apples are cheap and may be 
bought at any season of the year; and, when cooked, 


290 





WHOLESOME FOOD 


291 


they have nearly the same food value that they would 
have had if they had been cooked while they were 
fresh. One reason why dried fruit may sometimes 
have less food value than fresh fruit is that the best 
fruit is usually sold fresh, and the poorer fruit is dried. 

Cold Storage. — Large quantities of meat, fish, eggs, 
and other food are preserved fresh for many months 
by being stored in rooms which are kept at about a 
freezing temperature. The cold prevents the growth 
of bacteria and molds, and also prevents other changes 
which would naturally take place in the food. The 
principal objects of cold storage are to preserve a food 
while it is taken long distances to market, and to store 
it safely while it is abundant in order that it may be 
used when a new supply of the food cannot be obtained. 
The meat and fish which are used in large cities usually 
come to market in cold storage cars, and are kept in 
cold storage until they are used. It would be almost 
impossible to supply a large city with food without 
cold storage. 

All kinds of food that are not injured by cold 
may be preserved in cold storage. If a food is poor in 
quality, or is spoiled when it is placed in cold storage, 
it will be in the same, or a worse, state when it is taken 
out. If it is fresh and wholesome when it is placed in 
cold storage, it will remain wholesome for months. 

Keeping Food Fresh. — Many kinds of food, such 
as meat, milk, and cooked foods, usually turn sour or 
spoil within a very few days after they are brought 



292 


WHOLESOME FOOD 


into the kitchen, or prepared for the table, unless great 
pains are taken to keep them fresh. Food will not 
decay or turn sour if no bacteria or molds grow in it 
(p. 43). There are three principal ways of keeping 
food from spoiling in a kitchen or pantry: 

1. Food will not decay if it is kept dry, for bacteria 
will not grow without water. For this reason dry 
crackers will keep longer than bread, and dried beef 
will keep longer than fresh meat. Storing food in a 
dry place is a great help in keeping it fresh. 

2. Food will not spoil if it is kept cold, for bacteria 
grow very slowly in cold places. Frozen meat will not 
spoil at all, but freezing will injure most vegetables and 
fruit. A cold cellar or an ice box is a great help in 
keeping food fresh. 

3. If food is clean, it will have very few bacteria in 
it, and will keep fresh for a long time. Clean hands, 
clean dishes, a clean pantry, and keeping flies away 
from food, are all great helps in keeping food from 
spoiling. 

Sour Milk. — Milk spoils and turns sour more readily 
than most other common foods. The souring is caused 
by bacteria which fall into the milk with dust and dirt. 
Some kinds of bacteria growing in milk produce a 
sour substance called lactic acid , which curdles the 
protein of the milk and makes it like jelly. The bac¬ 
teria which turn milk sour are not usually harmful to 
grown persons, and do not spoil the milk for cooking. 
But any milk that is about to turn sour, or that con- 


WHOLESOME FOOD 


293 


tains many bacteria, is dangerous for children and 
babies, for it usually contains bacteria that produce 
sickness. 

Milk which contains harmful bacteria causes over 
a quarter of all deaths among babies. Nearly all in¬ 
testinal diseases among young children are due to 
unclean milk. Babies are more likely to have these 
diseases in summer than in winter, because most milk 
spoils quickly during 
warm weather, unless 
it is kept cool. 

Wholesome Milk. — 

Wholesome milk means 
milk which is clean and 
almost free from bac¬ 
teria. The dirt in milk 
comes from dirty cows, 
dirty stables, and the 
dirty clothes and hands 
of the milkmen. Many farmers object to sweeping 
and scrubbing the cow stables, currying and brushing 
the cows, washing the hands, and putting on clean 
clothes before milking, and carrying the milk at once 
to clean rooms. But these things must be done if 
milk is to be wholesome. What is called certified 
milk is pure because it is produced in this cleanly way. 
It is almost the only milk which may be safely fed 
to babies without first doing something to it to kill 
the germs. 



A Sanitary Cow Barn 

Wholesome milk is produced by clean cows 
in clean stables. 








2Q4 


WHOLESOME FOOD 


Some persons suppose that the harmful dirt may be 
strained from milk. This is not so. Thousands of 
bacteria will be washed off from every speck of dirt as 
large as a grain of sand, and there is no way of remov¬ 
ing them from the milk. If there is any dirt at all in 
the bottom of a milk pail or pitcher, or on the strainer, 
that milk is sure to be loaded with bacteria. It will 

not keep well, and will not 
be fit to be fed to small chil¬ 
dren, unless the bacteria 
in it are killed before they 
have time to grow and spoil 
the milk. j 

Dirt often falls into milk 
while it is being handled in 
open cans. The cleanest way 
of carrying milk to market is 
to place it in clean bottles as 
soon as it is milked, and then 
to seal the bottles, so that no 
dirt can get into them. 

Buy your milk from a man 
who has clean stables, clean 
cows, clean milk cans, clean hands, and clean clothes. 
Put it in a clean pail or pitcher, and keep it in a 
clean place, and away from flies. Choose bottled milk, 
if possible. 

Bad tastes in milk usually come either from dirt that 
falls into it, or from dirty pails and pitchers. Dried 



The Smelling Test for the 
Cleanliness of a Milk Pail 


An unpleasant odor in a milk can 
or pail, after it has been covered 
for half an hour, shows that it is 
dirty. 




WHOLESOME FOOD 


295 


milk left in the seams or on the sides of a milk can will 
decay and give off bad odors. When milk is put into 
the can, the bacteria of the decay grow in the milk 
and produce unpleasant odors and tastes. A test for 
the cleanliness of a milk can is to cover it tight for half 
an hour, and then remove the cover and smell of the 
inside of the can before the odors can escape. If there 
is an unpleasant odor, the can is dirty and the milk 
which is put into it will have the same odor and taste. 

Cooling Milk. — The 
number of bacteria in 
each drop of ordinary 
milk is several thousand 
while it is fresh, and is 
often many million after 
it has stood for a few 
hours in a warm room. 

The cleanest milk that 
can be bought or pro¬ 
duced will have a few 
hundred bacteria in 
each drop. These will 
not usually do harm if they do not increase in 
number. 

The easiest way to keep bacteria from growing 
is to cool the milk, for they will hardly grow at all 
if the milk is kept as cold as water in an ordinary 
well. Those who produce wholesome milk cool it 
as soon as it is milked, and keep it cool until it is 



A Sanitary Milk Room 


\ 


Wholesome milk is handled in a clean milk 
room and in clean utensils. This man is 
putting seal caps on the bottles. 








296 


WHOLESOME FOOD 


sold. Buy such milk if possible, and keep it in a 
cellar, or ice box, or other cool place. 

P a s t e u rizing 
Milk. — Heating 
milk boiling hot will 
kill all the germs 
that may be in it. 
This is called ster¬ 
ilizing it. But a 
boiling heat changes 
its taste. 

Heating milk to 
145 0 F. and holding 
it at that tempera¬ 
ture for thirty min¬ 
utes will kill the bacteria and disease germs which may 
be in the milk. This process is called pasteurization. 
The heat does not change the taste or the digestibility 
of the milk. Pasteurized milk is a safe food for babies, 
if the milk is fresh when it is heated, and is afterwards 
kept cool and clean. 

Food Sold on the Streets. — Food which is sold from 
carts, or is placed in front of stores for show, often be¬ 
comes soiled with dust and dirt from the street, and by 
flies which light upon it, and by the dirty hands of those 
who handle it. In all of these ways disease germs are 
often left upon food which is kept in front of stores. 
Food bought in these places may not be safe unless it 
is afterwards cooked so that the disease germs which 









WHOLESOME FOOD 


297 


may be on it will be killed. Boards of health often 
require that foods offered for sale shall be kept covered. 

Adulterated Food. — Some foods which appear to 
be pure contain substances which are added to lessen 
the cost or to make poor goods appear to be of good 
quality. These foods are called adulterated. Milk is 
sometimes adulterated with water, coffee with chicory 
root, and olive oil with cottonseed oil. Benzoate of 
soda is often added to catchup of poor quality in 
order to preserve it. 

A great many medicines which are advertised as 
harmless contain harmful drugs. Many pain killers 
and soothing sirups contain opium, and headache cures 
contain substances, such as phenacetin (fe-nas'e-tm), 
which produce dangerous weakness of the heart. 

Pure Food Laws. — Deceiving people by selling 
adulterated foods and harmful drugs is a crime. Many 
countries and states have laws that all packages of 
foods and drugs that are sold shall be marked with a 
list of the substances which they contain. The object 
of such laws is to enable those who buy the goods to 
know what kind of articles they are buying. 

Food Poisoning. — Poisoning by food may be caused 
by three conditions in the food: 

1. Decay, souring, fermentation, or spoiling. 

2. A disease in an animal from which meat or milk 
is taken. 

3. Human disease germs which have been put into 
the food by persons who handle it. 




298 


WHOLESOME FOOD 


Spoiled Food. — Ordinary decay or spoiling does not 
make food harmful or poisonous so often as was for¬ 
merly thought. The processes of souring or fermenta¬ 
tion are used in making certain foods, as butter, 
sauerkraut, and cheese; the outer parts of whole¬ 
some meat are often decayed; and farmers handle 
decayed substances safely as they use them for fer¬ 
tilizers. But there are a few kinds of bacteria which 
may produce dangerous poisons when they grow in 
food. One kind of poisoning is called botulism (bot'u- 
liz’m). The poisons of this sickness are formed by 
bacteria which usually produce offensive odors and 
tastes in the food in which they grow. They are found 
principally in canned goods which have not been 
heated sufficiently to kill the germs. A bad odor or 
taste of a can of food is a sign that the food may be 
dangerous to use. 

Meat of Diseased Animals. — Some diseases of 
lower animals may be transmitted to persons. The 
milk of a cow that has tuberculosis may contain living 
bacteria which may cause tuberculosis in a person who 
drinks the milk. 

There are some diseases which cause the flesh of 
animals to be poisonous to persons, although the germs 
of the disease may not grow in a person. Hog cholera 
is a disease of hogs which is something like measles in 
a person, and the meat of an animal that has the 
disease may be poisonous to man. The laws of some 
states forbid the sale of the meat of an animal that 



WHOLESOME FOOD 


299 


is thin or sick unless it is first inspected by a skilled 
veterinarian and all diseased meat is destroyed. 

Disease Germs in Food. — A third form of food poi¬ 
soning is that caused by human disease germs which 
come from diseased persons or carriers. Some common 
diseases which are spread by means of food are typhoid 



Why Foods Become Poisonous 

The poisons usually come from the dirty hands or the nose or mouth of 
a person who handles the food, or from the m^at of a sick animal. 


fever, scarlet fever, diphtheria, and a form of tonsillitis 
called streptococcus sore throat. 

The principal sources of disease germs in food are: 

1. Diseased persons or carriers who handle food. 

2. Impure water used in preparing food. 

3. Flies. 

If a food causes a disease, the principal reason usu¬ 
ally is that some diseased person or carrier has put the 







3 °° 


WHOLESOME FOOD 


germs in the food while handling it. A food handler 
infects food by means of soiled fingers, or by sneezing 
or coughing upon the food. Some cities have laws that 
food handlers in eating houses shall be examined, and 
that no diseased person or carrier shall be allowed to 
work in kitchens, or to handle food that is to be eaten 
raw. 

Milk is the principal food which may carry disease 
germs, for it is a liquid, and germs may be scattered 
through it readily and be carried to hundreds of people 
along a milk route. The germs may also grow and mul¬ 
tiply in milk more readily than in any other food. The 
great reason for pasteurizing milk is to kill the disease 
germs which may be in it. The heat of good cooking 
will kill most disease germs that are in food. 

Good Cooking. — Most kinds of food are more whole¬ 
some when they are well cooked than when they are 
poorly cooked or raw. Very few kinds are made less 
digestible by long cooking. Most foods made from 
grain cannot be digested readily unless they have been 
cooked for at least an hour or two. Oatmeal may be 
soft and may taste good after it has been cooked for 
only fifteen minutes, but it will not be readily digested 
unless it has been cooked for some hours. A good way 
of preparing it for breakfast is to put it on to boil in 
the evening, and let it cook slowly all night. 

Stews. — When meat is cooked, some of its juices 
and fat run out. If the liquid is thrown away, much of 
the nourishment and a great deal of the best tasting 




WHOLESOME FOOD 


3 OT 

parts of the meat are wasted. A good way of cooking 
meat is to make it into a stew or thick soup with pota¬ 
toes and vegetables. This method saves all the nour¬ 
ishment that is in the raw food. 

Another good way to cook meat is to place it in a 
hot oven for a few moments so that a crust will form 
over it quickly and prevent the juices from escaping. 
Then allow the oven to cool a little, so that the meat 
will cook slowly without burning. 

Desserts. — Pie, cake, and pudding are cooked 
mixtures of flour, sugar, fat, eggs, and fruit, and are 
usually hard to digest. A person would soon get tired 
of them if he had to live on them alone. Their food 
value is that of the flour, eggs, and other things of which 
they are made. 

QUESTIONS 

What is the cause of the spoiling of food ? 

How does dryness help to preserve food from spoiling? 

How does a low temperature help to preserve food from spoiling? 

How does cleanliness help to preserve food from spoiling? 

Why do foods remain fresh when they are properly canned ? 

How does drying affect the food value of fruit and vegetables? 

When food is properly kept in cold storage rooms, how is its food 
value affected? 

Name three ways in which food may be kept fresh in a kitchen or 
pantry. 

What is the cause of the souring of milk ? 

What is meant by wholesome milk ? 

Where do the bacteria that are in milk come from ? 

How may milk be produced almost free from bacteria ? 

Whv is bottled milk usually more wholesome than milk sold from 
large cans? 



3°2 


WHOLESOME FOOD 


Why is cold milk more likely to remain wholesome than warm 
milk? 

How is milk pasteurized ? 

Why is pasteurized milk usually more wholesome for babies than 
raw milk ? 

Why is food that is sold from stands on the streets likely to be 
unwholesome ? 

What is an adulterated food? , 

What is the object of pure food laws? 

What effect does good cooking have on food ? 

What effect has long cooking on the digestibility of vegetable foods ? 

Why is a stew one of the most nourishing forms of cooked meat? 

Describe some forms of food poisoning. 

Why should a diseased person not be allowed to handle food? 

What effect does cooking have on disease germs that are in food? 

For the Teacher. — How to keep food fresh and wholesome is one of the 
greatest problems with which city dwellers have to deal; but the topic is also 
important to rural people. 

Food properly kept in cold storage comes out of the storage as good as it 
went in. 

The possible loss of vitamins is not a sufficient reason for neglecting to use foods 
which have been canned or dried, for the missing vitamins may be easily supplied 
by the use of additional articles of food. 

The preservation of milk depends on two conditions, — cleanliness and 
cold. These two conditions must exist in the home as well as in the dairy, 
if milk is to be kept wholesome. If possible, take the pupils to a good dairy 
and show them how clean, wholesome milk is produced. Also demonstrate 
the odor test for the cleanliness of a milk pail. This same odor test is excellent 
for testing the cleanliness of table dishes after they have been washed. 

Milk handled by a diseased person is likely to spread his disease. Scarlet 
fever and diphtheria are frequently spread by a dairy workman who is only 
slightly sick. A person who has a cold, or sore throat, or diarrhoea, has no 
right to endanger the life or health of other persons by handling milk which 
is to be used by others. 

While any food which has become soured or otherwise spoiled may be un¬ 
wholesome, it is seldom the cause of diarrhoea or other form of food poisoning. 
Emphasize the danger of food poisoning by means of the meat of sick animals, 
or by means of disease germs left upon the food by persons who are sick or 
carry the disease germs on their unclean hands. 


CHAPTER XXV 


CARE OF THE NOSE AND MOUTH 

Focal Infections. — Disease germs may grow in a 
small part of the body and produce little harm in that 
spot, and at the same time their poisons may pass 
through the body and cause a severe sickness. A 
growth of disease germs continuing for months or years 
in a small part of the body is called a focal infection. 

The diseases which are caused by focal infections 
usually come on slowly, vary from day to day, and pro¬ 
duce discomfort and weakness without confining the 
sick person to his bed. Three common diseases often 
caused by focal infections are: 

1. Rheumatism in its various forms. 

2. Heart disease. 

3. Chorea, or St. Vitus’s Dance. 

The principal causes of the pains and aches which 
are often called rheumatism are focal infections, es¬ 
pecially of the tonsils and teeth. There is no cure for 
rheumatism as long as the focal infections which cause 
it are allowed to continue. The first step in the treat¬ 
ment of rheumatism is to discover and remove the 
focal infection which causes it. 

The parts of the body in which focal infections often 
occur are: 


303 



3°4 


CARE OF THE NOSE AND MOUTH 


1. The tonsils. 

2. The nose. 

3. The mouth. 

4. The teeth. 

Bacteria in the Tonsils. — If the tonsils are enlarged, 
they nearly always contain numbers of deep holes and 
pockets (p. 144). These holes may become filled with 
mucus, dead epithelium, and bits of food. Bacteria 
may lie in them undisturbed and cause the contents 
of the holes to decay. Disease germs also may lodge 
in them and produce tonsillitis and other forms of sore 
throat. On the other hand, disease germs may grow 
continuously in the holes without producing soreness of 
the throat, and yet they may form a focal infection 
which produces rheumatism and heart disease. White 
spots about the size of pinheads may sometimes be seen 
on the tonsils. The spots are the outer ends of masses 
of decaying substances, pus, and disease germs which 
fill the holes. Tonsils which are full of holes or contain 
white spots are dangerous to health, and should be re¬ 
moved by a surgeon. 

Bacteria in the Nose. — Bacteria may always be 
found growing in the nose. If its air tubes are large 
and open, the mucus washes most of the bacteria away 
and prevents them from becoming great in number, or 
doing harm. But if the air tubes are stopped up, bac¬ 
teria and disease germs may grow in the nose and pro¬ 
duce a cold, or sore throat, or pneumonia. 

Cleansing the Nose. — Cleansing the nose and keep- 




CARE OF THE NOSE AND MOUTH 


305 


ing its tubes open are necessary for health. This can 
usually be done by blowing the nose, for the mucus in 
the nose is its natural bath which washes away dirt and 
disease germs as fast as they are formed. Therefore 
a clean handkerchief is a very necessary thing for every 
man, woman, and child to carry and to use. 

The nose may be stopped up by a swelling of its 
lining, or a crooked bone in the nostril. If this is so, 
trying to blow the nose will make the stoppage worse. 
If your nose is stopped up and you cannot open it by 
blowing it lightly after holding your breath (p. 142), 
go to a doctor and have it examined and treated. 

The bones which surround the nostrils are partly 
hollow and contain cavities, called sinuses (sl'nus-gz), 
which are as large as the nostrils themselves. There 
is a large sinus, called the an'trum, on each upper jaw¬ 
bone under the eye, and another, called the frontal 
sinus , behind each eyebrow. These cavities open into 
the nose, and are really a part of it. If a person 
has a cold, disease germs may enter a sinus and cause it 
to become filled with thick mucus. The sinus may then 
become the site of a focal infection which makes the 
whole body weak and sick. . A person who has a cold 
in the head for weeks and blows much mucus from the 
nose probably has sinus disease and needs to be treated 
by a skilled physician. 

Bacteria in the Mouth. — The mouth is warm and 
moist, and contains many substances on which bac¬ 
teria may live. Many kinds of bacteria are always 


OV. GEN. HYG. 


20 


306 CARE OF THE NOSE AND MOUTH 


growing on the tongue and cheeks and between the 
teeth. The bacteria often produce decay and bad odors. 
Disease germs also often enter the mouth and grow 

there. Cleansing the mouth 
is very necessary for health. 
Washing the mouth with water 
will cleanse it. Merely rinsing 
the mouth with water will not 
wash away thick mucus or 
the coating from the tongue. 
When you brush your teeth, 
cleanse your whole mouth by 
rubbing the toothbrush over 
the tongue and the roof of the 
mouth. 

Bacteria in the Teeth. — 

and disease often grow in the 
teeth and gums. The teeth 
are more likely to become 
unsound and diseased than any other part of the body. 
Three common diseases of the teeth and gums are : 

1. Decay of the substance of a tooth. 

2. Abscess in the bone around a tooth. 

3. Abscess and soreness of the gums around a tooth. 
Decay of Teeth. — A tooth is composed of a kind of 

hard bone, called dentine (den'tm), which is covered 
with a thin layer of a harder substance, called enam'el. 
The center of each tooth has a hollow space containing 


Bacteria which produce decay 



Bacteria and an Epithelial 
Cell from the Mouth 


(Magnified 2000 times.) Bac¬ 
teria are the cause of a bad odor 
in the breath, and of much of the 
coating on the tongue. 






CARE OF THE NOSE AND MOUTH 


307 



A Decayed Tooth 


nerves and blood tubes. The tooth is fixed in the bone 
of the jaw with a kind of soft bone, called cement. 

Teeth are likely to decay unless they receive great 
care. The decay is caused by 
bacteria which grow in the teeth. 

Sound enamel is like the epithe¬ 
lium on the skin, and prevents 
bacteria from entering a tooth. 

But if the enamel is unsound or 
injured, bacteria may pass through 
it and cause the dentine to decay 
and go to pieces. If the decayed 
part reaches a nerve, the tooth 

may ache. A decayed tooth is like an 

n -, 1 . , open sore through which 

babies do not get the proper disease germs may enter 

minerals in their food, their teeth the body. 

do not form a sound enamel, and are likely to decay 

early. If a young child has a whole row of front teeth 

decayed, that child will usually be found to have been 

fed on condensed milk or other incomplete food while 

the teeth were growing. 

When a tooth has a hole in it, any bacteria which 
may be in the mouth may lodge in the hole and grow 
there. Persons sometimes catch diphtheria, tonsillitis, 
and tuberculosis because a few germs of these diseases 
have lodged in a decayed tooth and multiplied there. 
The two principal means of caring for teeth are: 

1. Brushing them. 

2. Having them filled. 




308 CARE OF THE NOSE AND MOUTH 


Brushing the Teeth. — Brushing the teeth removes 
dirt and bacteria from them and helps to prevent them 
and the gums from becoming diseased. Cleanse your 
teeth with a toothbrush and water two or three times 
a day. Brush their inner surfaces as well as their front 
sides, and brush the back teeth as well as the front ones. 
Rub the brush up and down as well as sidewise, so that 
the bristles will reach between the teeth. 

A tooth powder or paste is useful in cleansing the 
teeth when'you brush them. Many tooth powders con¬ 
tain powdered chalk, which helps to destroy harmful 
acids in the mouth. A soap which has no taste is also 
useful in cleansing the teeth and mouth. 

Particles of food may become wedged between the 
teeth so tightly that a toothbrush will not remove them. 
Push them from between the teeth with a toothpick 
made of soft wood, for a toothpick made of metal or 
hard wood may crack the enamel and start a hole in 
the tooth. You may also remove food and dirt from 
between the teeth by passing a thread between them. 

Filling Teeth. — You may save a decaying tooth by 
having a dentist remove the decayed part and fill 
the hole with a cement or a metal. The filling will close 
the hole and prevent bacteria from entering the tooth. 
Have a dentist examine your teeth every few months, 
and fill each hole as soon as it appears. In this way you 
can preserve your teeth for a lifetime, and prevent the 
ill health that comes from poor teeth. 

Diseased Gums. — When dirt is allowed to remain in 


CARE OF THE NOSE AND MOUTH 


3 ° 9 


the mouth and on the teeth, bacteria often grow be-, 
tween the gums and the teeth. The bacteria may 
slowly loosen the flesh from the teeth and bone until the 
gums form pockets in which dirt and disease germs col¬ 
lect. If the gums are healthy, their thin edges will 
cling closely to the necks of the teeth. But if the gums 
are diseased, their edges will be thickened and will hang 
away from the teeth, and the roots of the teeth will be 
bare up to the bone of the jaw. Disease germs may 
collect in the pockets of the gums, and may be a source 
of focal infection which produces sickness of the whole 
body. 

A common cause of disease of the gums is a dark-col¬ 
ored, mineral substance, called tar'tar, which collects at 
the roots of unclean teeth and pushes away the gums. 
Brushing the teeth regularly every day helps to prevent 
the tartar from forming; but it may be necessary to 
have a dentist scrape the tartar away every few months. 

Abscess of the Roots of Teeth. — Bacteria which 
grow in the gums around the teeth may extend down 
the cement and cause the teeth to become loosened and 
abscesses to form in the bone around the teeth. Bac¬ 
teria may also pass down through the center of a decayed 
tooth and cause an abscess to form in the bone around 
the deepest part of the root of the tooth. The abscesses 
may be a source of focal infection which produces rheu¬ 
matism and heart disease. The abscesses sometimes 
produce severe pain which drives a person to a dentist 
for relief. But often they are neither painful nor 


3io 


CARE OF THE NOSE AND MOUTH 



tender. A person may not be aware that he has 
trouble with his teeth, and yet they may be the 
cause of severe attacks of rheumatism and other forms 
of sickness. If a person suffers from rheumatism or 

heart disease, one of the first 
things to do is to have an X-ray 
examination of the teeth made 
to see if they have abscesses 
around their roots. If the teeth 
are found diseased, they must 
An X-Ray Picture of Teeth be cured before the sickness 

tZh; ‘"Cm'tT fZgl of the rest of the bod y can be 

c, metal cap. Cured. 

Care of the First Set of Teeth. — Two sets of teeth 
grow in the mouth during a lifetime. Those of the 
first set begin to drop out when a child is about six years 
old, and new ones grow in their places. The last of the 
first set are not replaced until the child is twelve or four¬ 
teen years old. 

The teeth of the first set are as likely to decay and 
produce sickness as those of the second set. Holes in 
those of the first set are as painful and as harmful to 
health as holes in those of the second set. Many chil¬ 
dren suffer for ten years or more with toothache and 
rheumatism while they are waiting for new teeth to grow 
in the places of those which are decayed or have ab¬ 
scesses at their roots. Brushing, filling, and treating 
the teeth of a three-year-old child are as necessary as the 
care of the teeth of its parents. Many schools employ 




CARE OF THE NOSE AND MOUTH 


3ii 


dentists to examine and treat the teeth of the pupils 
in order to protect them from diseases which come from 
focal infections. 

Sixth-year Molar. — In the first set of teeth there are 
only two double teeth on each side of each jaw. A 
third double tooth appears behind the 
two when a child is about six years old. 

This tooth is the first one of the second 
set, and is called the sixth-year molar. 

Many persons do not take care of it 



because they suppose that it is one of sixth-year Molar 
the first set, and that another tooth The teeth of an eight- 
take its place. 1 his tooth IS the tooth on each end is 
largest and most useful of all the double the sixth ' year molar - 
teeth, and if it is lost, no other tooth will grow in its 
place. Watch it, and have it filled as soon as it shows 
signs of decay. 


QUESTIONS 

What is a focal infection? 

How may diseased teeth or tonsils produce rheumatism? 

How can you recognize diseased tonsils? 

Of what use is the mucus which is produced in the nose? 

How may the nose be cleansed? 

How may the use of a handkerchief affect the health of the body? 
What is sinus disease ? 

How can you cleanse your mouth? 

Name three common diseases of the teeth and gums. 

Describe a tooth. 

What are some of the causes of decayed teeth? 

How may decayed teeth help to produce diseases? 

Why should the teeth be brushed every day ? 





CARE OF THE NOSE AND MOUTH 


Why should teeth be filled? 

What are some of the signs of diseased gums? 

How may diseased gums be prevented ? 

What is a danger from abscesses of the roots of teeth ? 

How may pain in a tooth be a protection to the rest of the body? 
What is a sixth-year molar f Why should it be given great care ? 


For the Teacher. —The nose and throat are of sufficient importance and 
prominence to justify great efforts to keep them clean and in a healthy, 
attractive condition; but a greater reason for their care is that of preventing 
heart disease, chorea, and so-called rheumatism, for all these diseases are 
usually caused by focal infections in the nose or mouth. 

Teach the pupils the necessity of cleansing the nose by blowing it. Inspect 
their handkerchiefs to see that they are clean. 

Also impress the pupils with the necessity of cleansing the tongue whenever 
they brush their teeth. The coating on the tongue may be the cause as well 
as the result of sickness. 

Cavities in decayed teeth may harbor disease germs; but a greater breed¬ 
ing place of disease germs is under diseased gums and around the roots of the 
teeth. A slow abscess may start between the gum and a tooth and travel 
along the root until the tooth is loose. This condition is called Rigg’s Disease, 
and may usually be prevented by the proper use of a toothbrush. The only 
proper treatment for an abscess deep around the root of a tooth is to have the 
tooth pulled out. 

A tendency to decay in teeth is the result of improper food while a person is 
very young and the teeth are forming. Experiments in feeding animals, such 
as squirrels, in which the front teeth grow continuously during life, show that 
a tooth will be soft in the section which grows while improper food is given, and 
hard in the section which grows while the food is proper. The soft sections de¬ 
cay like soft human teeth. Tooth substance which is formed while the food 
is improper is like a section of concrete which is made from poor cement. 

Emphasize the danger from infected tonsils and the need of having them 
removed. White spots on a tonsil are sure indications of disease. 


CHAPTER XXVI 


INFECTIOUS DISEASES 

Cause of Infectious Diseases. — Those forms of sick¬ 
ness that are caused by living germs growing in the body 
are called infectious diseases (p. 37). Some of the 
common infectious diseases are colds, measles, scarlet 
fever, diphtheria, typhoid fever, whooping cough, tuber¬ 
culosis, tonsillitis, and pneumonia. Each disease is 
caused by a particular kind of germ which is different 
from the germs of all other diseases. 

A person will not have an infectious disease unless the 
germs of that disease enter his body. Catching a dis¬ 
ease means taking its germs into the body. Taking 
disease germs into the body is called infection. 

Cultures. — The germs of most diseases may be grown 
in glass tubes or dishes outside of the human body when 
they are planted in the proper substances. An artificial 
growth of disease germs outside of the body is called a 
cuVture. Physicians often make cultures of germs taken 
from sick persons in order to discover the kind of disease 
germs which are causing the sickness. When a physi¬ 
cian makes a culture, he takes some of the blood or 

0 

waste matter from the sick person and plants it in a 
tube in order that the disease germs may grow and 

313 



314 INFECTIOUS DISEASES 

multiply until they may readily be seen and studied. 
Boards of health require that cultures shall be made in 
all cases in which diphtheria may be suspected. 



A Culture Tube 

The substance in the tube consists mainly of the serum of beef blood, and is an 
excellent soil on which disease germs grow when they are removed from the body 

and planted in the tube. 

Conditions for Spreading a Disease. — In order that 

a disease may spread, four events must occur: 

1. Its germs must grow in the body of a person or 
lower animal. 

2. The germs must be given off from the body. 

3. They must travel to another person. 

4. They must grow and multiply in this person’s 
body. 

Source of Disease Germs. — Germs of an infectious 

disease nearly alwdys come only from some person or 
animal that has the disease. It is often said that they 
come from dirt, sewage, and decaying substances, but no 





INFECTIOUS DISEASES 


3 i 5 


disease germ of any kind will be found in such things 
unless that kind of germ is first planted in them. 

There are three classes of persons who produce disease 
germs: 

1. Those who are severely sick. 

2. Those who are mildly sick, or are beginning to be 
sick, or are nearly well. 

3. Well persons who carry disease germs in their 
bodies without being sick. 

Those who are severely sick stay at home and in bed. 
They cannot go to other persons to spread their disease 
germs to them; and other people know that they are 
sick, and fear to go near them. But those who are 
mildly sick often go among other people and do not 
think about the disease germs which they may be 
spreading. Most diseases are now spread by those 
who are mildly sick, and are ignorant of the danger 
which they are to others. 

Carriers. — The germs of a few diseases may grow in 
a small part of a person’s body without causing a sick¬ 
ness. A well person who has disease germs growing in 
his body is called a carrier. Two kinds of disease germs 
of which well persons are sometimes carriers are those of 
diphtheria and typhoid fever. When a number of chil¬ 
dren become sick with diphtheria in a school, the cause 
may usually be traced to a well person who is a car¬ 
rier of diphtheria germs. A carrier of disease germs 
can spread a disease as readily as a person who is sick 
with the disease. 



3 l6 


INFECTIOUS DISEASES 


How Disease Germs Leave the Body. — Disease 
germs leave the body of a sick person or a carrier in five 
ways. The four principal ways are through the intes¬ 
tine, kidneys, nose, and mouth. These are also the 
principal gateways through which excretions leave the 
body (p. 198). Nearly every excretion from the body 
of a diseased person may contain germs of the disease 
(p. 201). If all excretions from the sick were destroyed, 
few kinds of disease germs could reach other persons to 
infect them. 

Disease Germs and the Skin. — The fifth way in 
which disease germs pass off from the body is through 
sores or other openings on the skin. Disease germs can¬ 
not pass through healthy epithelium (p. 186), but they 
may pass from spots on which the epithelium is destroyed. 
Smallpox and chicken pox are two diseases whose germs 
leave the body through sores on the skin. 

Biting insects may pierce healthy epithelium with 
their bills and take up disease germs with the blood 
which they suck, and may inject the germs into the next 
person whom they bite. Malaria is a common disease 
which is spread by means of the bites of mosquitoes 
(p. 232). 

The healthy skin of any person may indirectly be the 
means of spreading diseases when it is soiled with the 
excretions of the body (p. 201). 

Disease Germs and the Air. — Disease germs do not 
pass off from the body with the breath during quiet 
breathing. But when a person coughs, or sneezes, or 




INFECTIOUS DISEASES 


3 i 7 


blows his nose, or spits, he usually expels little drops of 
mucus and saliva, and these may contain disease germs. 
If the drops are blown upon the face of another person 
that person is likely to take living germs of the disease 
into his body. Infection by means of tiny drops of 
excretion blown from the nose and throat is one of the 
most common ways of spreading diseases. Five feet 
is about as far as the drops usually float, for they are 
heavier than air and soon fall to the ground. 

Disease germs may rise with dust, if the floor of a 
room contains saliva and other excretions from a dis¬ 
eased person. Most foul air is dusty, and often contains 
disease germs which have risen with the dust. 

It is almost impossible to find disease germs in the 
outdoor air, even a few feet from a person who has an 
infectious disease, or near a house in which he is sick. 

For the effects of bad weather see page 178. 

Routes of Infection. — After disease germs have left 
the body of a sick person, they must travel to another 
person and enter his body before they can produce 
a disease. In order to understand how disease germs 
pass from the sick to the well, one must remember the 
following facts: 

1. Disease germs outside of the body are found in 
company with excretions from the bodies of the sick. 

2. They rarely grow and multiply outside of the 
body, except now and then in milk and other food. 

3. They usually die in a few hours or days, and often 
in a few minutes after they leave the body. 



INFECTIOUS DISEASES 


3x8 

4. They usually travel from sick persons to the well 
by the short, direct routes by which excretions are 
carried from one person to another. 



Diagram of Common Routes of Infection 


The principal means by which disease germs are car¬ 
ried from the sick to the well are: 

1. Contact. 

2. Dirt. 

3. Impure water and food. 

4. Flies and other vermin. 

Contact Infection. — The shortest and most direct 
route by which disease germs pass from the sick to the 
well is that called contact , in which the sick persons them¬ 
selves put their disease germs almost directly into the 
bodies of those who are near to them. When two per- 









INFECTIOUS DISEASES 


3 I 9 


sons are near each other face to face, it is almost impos¬ 
sible to avoid blowing drops of mucus and saliva into 
each other’s faces while talking, laughing, coughing, 
or sneezing. Disease germs are also carried directly to 
other persons by means of kissing, and holding children 
on one’s lap. Diseases are spread by contact more 
often than by any other method. 

It was formerly believed that any one who merely 
called on a sick person would be likely to carry away 
disease germs on his clothes, and so would endanger 
others even if he did not catch the disease himself. This 
belief is not true, unless the visitor is extremely dirty and 
careless. Disease germs do not fly through the air, or 
cling to clothes for a time and fly off again to attack 
another person. A visitor will seldom carry disease 
germs away from a sick room unless he catches the dis¬ 
ease himself. 

Disease Germs and Dirt. — A route of carrying in¬ 
fection, which is somewhat longer than the contact 
route, is that by means of articles which have been soiled 
with the excretions of sick persons. The germs will 
be on soiled handkerchiefs, towels, dishes, bedding, 
clothes, and toys which the sick persons have used. If 
these things are washed well or boiled, the germs on 
them will be killed. 

Dirt and filth will often contain disease germs, but 
not always. There are usually no disease germs in 
fresh ashes, or in the clean sand of the seashore, or in the 
fresh dust of a flour mill, or in the mud of a mountain 


3 2 ° 


INFECTIOUS DISEASES 


brook. The kind of dirt in which they will be found is 
that which contains excretions from the bodies of sick 
persons or lower animals. Whatever is soiled with any¬ 
thing which comes from a diseased person’s nose, mouth, 
intestine, or kidneys may contain germs of the disease. 
The principal reason for keeping the body and every¬ 
thing about it clean is to be free from disease germs. 

Disease Germs in Water and Food. — A still longer 
route of carrying infection is that by means of impure 
water and food. Water that contains sewage may 
carry disease germs into the body. Food may con¬ 
tain disease germs when it is prepared with impure 
water, or when some one handles it with soiled hands, or 
sprays disease germs over it by coughing or sneezing. 

Disease Germs and Vermin. — Disease germs often 
reach the body by means of flies and other vermin 
(see Chapter XIX). 

How Disease Germs Enter the Body. — The two 

gateways through which the germs of most diseases 
enter the body are the nose and the mouth. None of 
the germs of the common infectious diseases can enter 
the body through a healthy skin, for the epidermis will 
keep them out if it is sound (p. 186). Diseased persons 
and their excretions may be handled with safety if there 
are no cuts, or scratches, or sores on the skin. 

If the epidermis is injured or diseased, germs may 
pass through it and enter the blood and the lymph. 
This is the way in which the germs of pimples, boils, and 
sore wounds enter the flesh. Malaria and yellow fever 



INFECTIOUS DISEASES 


3 21 


are caused by germs which are put into the blood by the 
bites of mosquitoes. Hydrophobia is caused by germs 
which are put into the flesh by the teeth of dogs or cats 
which have the disease. 

Incubation Period. — Disease germs which enter the 
body usually do no harm until they have grown and 
multiplied to countless millions. They must grow for 
hours or days before they become numerous enough to 
produce sickness. The length of time between the en¬ 
trance of the germs and the beginning of the sickness is 
called the incubation period. A common cold has an in¬ 
cubation period of about two days ; scarlet fever, a week 
or less ; and measles, two weeks. 

Protection against Disease Germs. — Every person 
often takes disease germs into his body without catching 
a disease, for the body can destroy the germs if only a 
few enter it. About a thousand germs must enter the 
body at one time in order that any of them may be able 
to grow and produce a disease. The body destroys 
disease germs in two ways. First, the white blood cells 
seize the germs and destroy them (p. 96). Second, the 
liquid part of the blood contains substances which 
hinder, or prevent, the growth of the germs. Some 
persons have a larger quantity of these substances than 
others, and so they escape diseases which others catch. 
But nearly every person will catch a disease if he takes 
a great number of germs into his body at once. 

Immunity. — An infectious sickness shows that the 
blood of the sick person lacked the defensive substances 


OV. GEN. HYG.-21 


3 22 


INFECTIOUS DISEASES 


when the germs entered his body. But after the disease 
germs have grown for a few days, the blood usually 
forms the protective substances in such quantities that 
they overcome the disease germs and end the sickness. 
The body may then continue to form the protective 
substances for weeks or a lifetime. A person cannot 
usually take measles a second time because he con¬ 
tinues to produce the defensive substances after he re¬ 
covers from the first attack. A person whose blood 
contains the defensive substances against the germs of 
a disease is immune to that disease. 

There is a protective substance against each disease. 
That against measles will not prevent chicken pox, and 
that against typhoid fever gives no protection against 
pneumonia. Some persons have the substances which 
protect them from a number of diseases, but no one has 
them against all diseases. 

Diphtheria Antitoxin. — An example of a protective 
substance which is formed by the blood is diphtheria 
antitoxin. The antitoxin will overcome the poisons 
which are produced by diphtheria germs. About half 
of all persons have the antitoxin in their blood, and are 
immune to diphtheria. If a person has diphtheria, his 
blood lacks antitoxin; but if the antitoxin is injected 
into his body, it will act as well as that which the body 
naturally forms. 

The antitoxin which is used in treating diphtheria is 
produced by horses. Diphtheria germs are grown in a 
liquid, and a few drops of the liquid are injected into 



INFECTIOUS DISEASES 


323 


a horse. The animal is made slightly sick, but soon re¬ 
covers. A larger quantity of the liquid is then given, 
and is repeated once or twice a week in increasing 
amounts. In about three months, the horse can take a 
pint of the liquid without harm, for the injections cause 
the animal to form great quantities of antitoxin in its 
blood. The antitoxin which is used in treating diph¬ 
theria is the purified blood serum of a horse which has 



Diphtheria Antitoxin 

The antitoxin is given under the skin by means of a hypodermic syringe. 


been treated in this way. A horse will produce 
enough antitoxin every three months to cure hundreds 
of persons who have diphtheria. 

Horses are also used for producing antitoxins and 
other protective substances against lockjaw, meningitis 
(men-m-jlTis), pneumonia, anThrax, and other diseases. 

Vaccines. — Protective substances against a disease 
may be produced by the body when the germs of that 
disease in a dead or greatly weakened form are injected 
into the body. Producing immunity to a disease by 
means of injections of its germs is called vaccination 
(vak-si-na'shun). Injections of dead typhoid fever 
germs were given to every American soldier in the World 











3 2 4 


INFECTIOUS DISEASES 


War, and as a result typhoid fever was almost unknown 
in the American army, although the disease had always 
been common in previous wars. 

Vaccination for Smallpox. — Cows sometimes have a 
mild disease called cowpox. The germs of cowpox are 
like very weak germs of smallpox. When a person is 
vaccinated, a few of the germs from a calf are rubbed 
into a small scratch on his arm. The germs grow and 
cause a blister or sore to form on the spot. After two or 
three weeks the spot heals and leaves a scar. While the 
germs are growing in the flesh, they cause the blood to 
form a protective substance which will remain in the 
body, and will prevent smallpox germs from growing if 
they should enter the body. One vaccination will usu¬ 
ally protect a person from smallpox for many years, and 
often for a lifetime. The vaccinated persons who do 
take the disease have it very mildly. A good rule is 
to vaccinate every child when he begins to go to school, 
and again at about the age of twelve. 

Before the year 1800 smallpox was so common that 
everybody expected to have it, and more persons died 
from it than from any other disease. About that year 
vaccination was discovered by an English doctor named 
Edward Jen'ner, and was at once widely used. Since 
that time there has been less and less smallpox among 
civilized people. There is almost no smallpox in the 
city of New York, because the school children and most 
grown persons in that city are vaccinated. 

Some persons refuse to be vaccinated because they fear 



INFECTIOUS DISEASES 


3 2 S 


j? i>- s-' ; ; if. ■ r mi' : P 

* 


that the vaccination will produce a disease. If the arm 
is swollen, or if the vaccinated person is made sick, it is 
because dirt and disease germs were allowed to enter the 
vaccinated spot. Pure vaccine germs do not cause pain 
or sickness, and do not 
leave any harmful sub¬ 
stance in the body. The 
vaccine that is now 
supplied by boards of 
health is pure, and is 
put up in sealed glass 
tubes. It is easy to put 
the vaccine into the 
arm in a clean and safe 



bePARTMENT OF HEALTH* CITY QF NEW YORK, 

VACttwg VWUS 


Smallpox Vaccine 


The vaccine is put up in small glass tubes 
whose ends arc sealed by heat. A common 
-p. . sewing needle that can be passed through a 

Way. UlSeaSe germs dame for cleansing is used for making a tiny 

may be kept out of skin scratch on which the vaccine is planted ' 


a vaccination sore just as surely and readily as they may 
be kept out of drinking water, or out of a wound which 
a surgeon makes at an operation. If this is done, vac¬ 
cination is safe, and does not produce any bad results. 


QUESTIONS 

What is the cause of infectious diseases? 

Name some of the common infectious diseases. 

What is a culture? 

% 

What is the great source of disease germs? 

Where do disease germs which may be in dirt and sewage come from ? 
What is a carrier? 

Why does a person mildly sick spread disease germs more readily 
than one who is dangerously sick ? 











326 


INFECTIOUS DISEASES 


Through what four natural gateways do disease germs leave the 
body of a sick person? 

When may the skin give off disease germs? 

When may the expired breath contain disease germs? 

What is the source of disease germs in dusty air? 

What are the principal means by which disease germs are carried 
from the sick to well persons? 

What is contact infection? 

Describe infection by means of toilet articles. 

When may water or food contain disease germs? 

What are the two gateways through which disease germs usually 
enter the body? 

What disease germs usually enter the body through the skin ? 

What is meant by the incubation period of a disease ? 

By what two means does the body try to destroy disease germs 
which enter it? 

What is immunity? 

Describe diphtheria antitoxin. 

Describe typhoid vaccine. What results followed its use in the 
army ? 

Describe smallpox vaccine and the manner by which it protects the 
body against smallpox. 

What has been the effect of vaccine on the prevalence of smallpox? 

For the Teacher. — The object of this chapter is to state the modern con¬ 
ception that every case of infectious disease is the result of disease germs 
which are introduced into the body from a previous case of the disease. This 
is in distinction from the old conception that the principal causes of infectious 
diseases were cold, dampness, and bad weather. When a disease develops, 
the modern health officer looks for the person from whom it was caught. 

Emphasize the modern conception of a carrier, or a person in whom disease 
germs continue to grow after apparent recovery from a disease which may have 
been so mild that the existence of sickness was not suspected. 

Develop the concept of the four common routes of the transmission of 
disease germs from one person to another by means of contact, dirt, impure 
water or food, and vermin. 

Develop the concept of the formation of protective substances, such as 
diphtheria antitoxin, which prevent disease germs from growing in the body. 
Also explain that the body can be induced to form the protective substances 
by the use of a vaccine, such as that against smallpox. 


CHAPTER XXVII 


PREVENTION OF INFECTIOUS DISEASES 

Means of Prevention. — Nearly all infectious dis¬ 
eases may be prevented. Physicians and health offi¬ 
cers know the source of disease germs, the routes by 
which they travel from the sick to the well, and 
the means of making the body immune to many 
diseases. But physicians and health officers cannot 
control diseases unless the people themselves have 
this knowledge, and also the willingness and desire to 
put themselves to some trouble in preventing their 
diseases from spreading to others. The control of in¬ 
fectious diseases is like the control of fires. Health 
departments put out the big epidemics of diseases, 
but only the people themselves can put out the little 
fires of infection before they become epidemics. 

Finding Cases of Infectious Diseases. — In order to 
control the spread of diseases, the health officer must 
find the persons who are the sources of the disease 
germs. Every case of infectious disease comes from a 
parent case, and is preceded by an ancestral line of cases 
reaching back in time like a person’s parents and 

327 




328 PREVENTION OF INFECTIOUS DISEASES 


GI?eAT~GRfl<NDPAR£rt? CASC 



The Ancestry of a Case of Infectious Disease 

Every case comes from a parent case, and that from a grandparent case, and so 
on back through a long line of sick persons. 

grandparents. Any case may also have produced 
other cases, which are then like a person’s children. 

The first step in preventing the spread of a disease 
is to find all the sick persons who are producing the 
germs of the disease. If every such person were known 
and controlled, no other persons would catch the disease. 
The health officer finds the infected persons from two 
sources of information : 

1. The reports of physicians who are called to treat 
the persons. 

2. A search for cases which are not seen by physicians. 
The laws of most states require every physician to 

inform the health officer or the board of health about 
the cases of infectious disease which he sees. Among 




PREVENTION OF INFECTIOUS DISEASES 329 

the common diseases which must be reported are chicken 
pox, diphtheria, measles, mumps, scarlet fever, tuber¬ 
culosis, typhoid fever, and whooping cough. 



Diagram of Methods of Reporting a Case of Infectious 
Disease by a Physician and a Nurse 


Many cases of infectious disease are mild, and those 
who see the sick do not recognize the disease, and do 
not call a physician or report the sickness to the health 
department. Most epidemics start from mild cases 
which have not been reported. When an infectious dis¬ 
ease occurs in a town, the physicians and nurses of the 
department of health will search for such cases, and 
will visit the homes of children who are absent from 
school, and will call on persons whom they hear to be 
slightly ill. They often find many cases which have not 
been reported, because no doctor had been called. 

Date of Onset. — When a health officer investigates 
















330 PREVENTION OF INFECTIOUS DISEASES 


a case of infectious disease, he tries to find out its date 
of onset , which is the day on which the sick person 
showed or felt the first signs of illness. This date is 
important, because the sick person can usually give off 
the germs of his disease from the day of the beginning 
of his sickness. The health officer finds the date of 
onset by questioning the sick person or those who have 
been with him. 

Finding Contacts. — Having found the date of onset, 
the health officer searches for the persons, called con¬ 
tacts, who have been with the sick person on and since 
that date, because some of these persons may have 
caught the disease. The contacts may be divided 
into two groups: 

1. The immunes, or those who either have had the 
disease or have received an antitoxin, or vaccine, 
against it. These cannot take the disease, and noth¬ 
ing need be done with them. 

2. Those not immune. These need to be watched 
during the incubation period of the disease (p. 321) in 
order to see whether or not they come down with the 
disease. 

Finding the Source of Infection. — After a health 
officer has found the date of onset of a person’s disease, 
he counts backward from it for the time of the incu¬ 
bation period of the disease in order to find the date 
of exposure, which is the date on which the disease 
was caught. The health officer then tries to find out 
where the sick person had been at that time, with whom 



PREVENTION OF INFECTOUS DISEASES 331 


he had been in contact, and what he had been doing. 
In this way he is often able to find the source of the 
disease. Sometimes he finds it to be either a carrier 


vS'jMt A- t 

m-/7\ 


CM-ZV 


May 17, date on which the Smith child probably caught the measles. 
(Date of infection.) 

The Jones child was found by the nurse to have been absent 
from school for three days about this time, with a slight breaking 
out, and to have played with the Smith child and the Green 
children. 

May 27, the Smith boy first felt sick. (Date of onset.) 

^\\\ X W Three Brown children, contacts with Smith child on May 27, 

\ 


X to be watched for two weeks to see if they have caught measles. 


<MY-30V&v 


ry> y-ji 




On May 30, the Smith boy, who has measles, first had a physician. 


On May 31, two Green children are found by the nurse to be 
mildly sick with measles. 


Diagram of the Results Found at an Investigation of a 

Case of Measles 

The physician saw the Smith boy on May 30, and reported the case to the health 
officer. The nurse from the health department found that about May 17 
the Smith boy had played with the Jones boy, who had measles in a mild form and 
had no doctor, and that two Green children were with them. A visit to the Green 
children showed that they too were sick with measles. 


or a mild case that had not been reported, or the use 
of impure water or milk. If the source is either 
water or milk, several persons are usually made sick 
at the same time. 

Means of Preventing the Spread of Diseases. — 

There are four principal methods of preventing the 
spread of diseases: 







332 PREVENTION OF INFECTIOUS DISEASES 


1. Controlling the persons who are the sources of 
disease germs. 

2. Destroying germs as they leave the bodies of the 
sick. 

3. Breaking up the routes by which the germs travel 
from the sick to the well. 

4. Making the body immune to the germs which 
enter it. 

Any one of these four means would stop the spread 
of almost any disease if it could be applied in a per¬ 
fect manner, but the use of all four is usually neces¬ 
sary. 

Control of Infected Persons. — The most direct 
route for the spread of disease is that by contact of 
the infected persons with those who are well (p. 318). 
When a health officer has found a case of infectious 
disease, he causes the infected person to remain away 
from other persons. There are three degrees of re¬ 
straint which a health officer may- impose ; namely: 
1, quarantine (kwor'an-ten) ; 2, isolation; and 3, a 
lesser degree of restraint than either. 

The most complete degree of restraint is that called 
quarantine, by which the sick person and all the 
members of his family are compelled to stay in 
a house or yard, and no one is allowed to enter it, ex¬ 
cept the doctor and nurse. This was the old method, 
and was used in times when the cause of infectious 
diseases was supposed to be spirits or gases which 
passed off from the sick and attacked well persons in 



PREVENTION OF INFECTIOUS DISEASES 333 


some unknown way. It is now seldom used, except 
with extremely ignorant or careless people, who cannot 
be trusted to obey the health officer. 

The modern method of controlling infected persons 
is that called isolation. It consists in keeping the in¬ 
fected persons apart from those who are not immune to 
the disease. A child with scarlet fever, for example, is 
kept in one part of a house or yard, and the other mem¬ 
bers of the family are allowed to go about as usual, 
except that contacts who are not immune must be 
watched and possibly isolated during the period of 
incubation of the disease. Isolation is a safe method 
among people who are well-informed and are willing to 
help in preventing the spread of a disease. It is used 
in measles, ^scarlet fever, pneumonia, and most other 
infectious diseases, especially in those in which cough¬ 
ing and sneezing occur. 

Lesser degrees of restraint which a health officer 
may require of the infected persons are: 

1. They shall not go to meetings or among 
crowds. 

2. They shall not go near children. 

3. They shall not work where they handle food. 

4. They shall avoid spreading disease germs from 
the nose and mouth by spitting, coughing, or other 
means. 

The degree of restraint which -the health officer im¬ 
poses will depend partly on the nature of the disease, 
and partly on the intelligence and character of the 


334 PREVENTION OF INFECTIOUS DISEASES 


infected person, and of the people among whom the in¬ 
fected person lives or goes. 

Disinfection of Excretions. — A person spreads dis¬ 
ease germs by means of his excretions. If all the liquid 
and solid excretions of an infected person were caught 
and destroyed as soon as they leave the body, that 
person could not spread diseases. This cannot always 
be done when a person is coughing and sneezing and 
producing a great deal of mucus in the nose and throat, 
and so quarantine or isolation is necessary in some 
diseases. But every person, whether he is quarantined 
or isolated or not, should take care of his excretions and 
destroy them. Destroying the disease germs in ex¬ 
cretions is called disinfection. 

The principal methods of disinfection are the fol¬ 
lowing : 

1. Catching the discharges of the nose and throat 
on handkerchiefs and napkins (p. 202). 

2. Killing the germs on clothes, toilet articles, and 
the skin by cleanliness, laundering, and bathing. 

3. Disposing of sewage in a proper manner (p. 204). 

4. Allowing plenty of sunlight in houses and rooms 
(p. 168). 

If all these means are used in a sick room, no disease 
germs will be left there ; and when the sick person gets 
well, the room will be safe for use if the room and 
furniture are given a good house cleaning, and if the 
bedding and all toilet articles which have been used in 
the room are well washed and cleaned. 


PREVENTION OF INFECTIOUS DISEASES 335 


Disinfectants. — Substances, called disinfect'ants, are 
sometimes used in order to kill disease germs. Some 
common disinfectants are formalin and chloride of 
lime. They are of special value in the sick room where 
disease germs must be destroyed quickly. 

It was formerly the custom to fumigate a sick room 
with a disinfecting gas at the end of an infectious dis¬ 
ease, but fumigation is now seldom used, and is unnec¬ 
essary if the room is properly cleaned. It is a good 
plan to put a disinfectant in the wash water which is 
used in cleaning the sick room. 

Breaking up the Travel Routes of Disease Germs. — 
The chief route for the spread of disease germs, 
namely, contact (p. 318), is broken up by means of 
isolation. On nearly all other routes the germs steal 
rides on things which enter the mouth, especially food 
and water. 

A common route is that by fingers , in which the 
disease germs start from the body of the sick person 
with some excretion, stop for a while on dirty fingers, 
and may again stop on food which is touched by the 
fingers, and then pass into the body when the food is 
eaten. There are two ways of breaking this route: 

1. The germs may get lost if the hands are washed. 

2. They may be killed if the food is cooked. 

The fly route of the germs leads to a collection of 
excretions of the body; then to a fly that stops at the 
excretions; then to food over which the fly crawls; 
and finally into the body of the person who eats the 



336 PREVENTION OF INFECTIOUS DISEASES 


food. The fly route may be easily broken in three 
ways: 

1. The excretions may be destroyed. 

2. They may be covered so that the fly cannot 
reach them. 

3. The food may be screened so that the fly cannot 
reach it. 

Another common route is that by means of drinking 
water , in which the germs start from the body with an 
excretion, stop for a while in slops or other sewage, stop 
again in drinking water into which the sewage runs, and 
finally reach the body when the water is swallowed. The 
ride of the germs is broken if the sewage is properly 
purified, or if its route of flow does not cross the route 
of flow of the drinking water. 

One of the most inportant objects in the study of 
hygiene is to learn the courses of the routes of infection 
and the points at which they may easily be broken. 

Producing Immunity. — There is always the danger 
that a route of infection will be left unguarded, and that 
some disease germs may be abL to reach the body alive. 
But the germs can do no harm if the body can kill 
them before they can grow. The body can be made 
immune to diphtheria and lockjaw by injections of 
the antitoxins against those diseases. It can be made 
immune to smallpox, typhoid fever, and rabies by 
means of vaccines for those diseases. New discover¬ 
ies are continually being made regarding antitoxins 
and vaccines. 



PREVENTION OF INFECTIOUS DISEASES 337 


Disease in a School. — When several children in a 
school have a disease, such as scarlet fever or diph¬ 
theria, there is often a demand that the school be closed 
in order to stop the disease from spreading. It is 
usually best that the school be kept open for the fol¬ 
lowing reasons: 

1. The children are under the eye of a watchful 
teacher, and often of a school nurse also, and a slight 
sickness will be noticed. 

2. Children behave better in school than in almost 
any other place. Here they are orderly and clean, 
and are taught what to do in order to prevent the 
spread of disease. 

3. Children out of school, having nothing to do, visit 
one another and come much closer together than they 
do at school. 

4. If there is a school nurse, she will keep track of 
the children. 

Diphtheria. — Diphtheria is one of the most common 
and most dangerous diseases in the United States. 
The methods of dealing with it will illustrate how a 
health officer deals with other infectious diseases. 

Diphtheria is caused by diphtheria germs growing in 
the throat. The germs usually cause a coating, or 
membrane, like a thick, white scab, to form on the 
tonsils. The germs also form poisons, or toxins, 
which produce great weakness and sometimes death. 
There is usually some sore throat, or other signs that 
the throat is diseased. Whenever there is anything 


OV. GEN. HYG. — 2 2 


338 PREVENTION OF INFECTIOUS DISEASES 


wrong with the throat, diphtheria is the disease to 
think about. There are two things for a physician to 
do in order to find out whether or not the disease 
is diphtheria: 

1. Look into the throat for a membrane. 

2. Take a culture from the throat (p. 313). If diph¬ 
theria germs are present, the disease is diphtheria, even 
if little or no membrane is present. 

The lives of many children every year are lost from 
diphtheria because they refuse to let a physician look 
into their throats or take a culture. A life may depend 
on the prompt discovery and treatment of diphtheria 
when the disease exists. 

Diphtheria often looks like a disease called tonsillitis. 
The only safe rule is to take a culture from every 
sore throat. A physician or nurse does this by touch¬ 
ing a small swab to the tonsils and then rubbing it 
over a jelly like substance in a glass tube. The swab 
carries germs from the throat to the tube, where they 
grow, and in a day or two the germs may be easily- 
recognized. Many states and cities support labora¬ 
tories in which diphtheria cultures are examined free. 

Diphtheria germs travel from one person to another 
over three principal routes: 

1. Direct contact. 

2. Milk and other foods into which diphtheria 
germs have been put. 

3. Handkerchiefs, towels, and dishes on which some 
one has left diphtheria germs. 


PREVENTION OF INFECTIOUS DISEASES 339 



The Main Routes by Which Diphtheria is Spread 

There are three things for a physician to do with a 
person who has diphtheria: 

1. Give him a dose of diphtheria antitoxin (p. 322). 

2. Isolate him (p. 333). 

3. Have the nurse destroy the excretion from his 
nose and throat (p. 334). 

Antitoxin is an almost sure cure for diphtheria if it 
is given during the first day or two of the disease. It 
acts by destroying the poisons which are produced by 
the disease germs. If it is given late, it cannot over¬ 
come the damage which the poison has already done, 
just as water cannot restore the burned parts of a 
building. Antitoxin is so useful in diphtheria that 
some states supply it free. 

















340 PREVENTION OF INFECTIOUS DISEASES 


The laws of most states require that every case of 
diphtheria shall be reported. Since the time when 
cases have been reported, cultures examined free, and 
antitoxin given away, the number of deaths from diph¬ 
theria has been reduced to less than one quarter of their 
former number. There are hardly any deaths when the 
disease is recognized and antitoxin is given early in the 
disease. 

Diphtheria Carriers. — The isolation of a person 
for diphtheria is continued until no diphtheria germs 
are found in two successive cultures taken at least a 
day apart. The germs sometimes continue to grow in 
the throat for weeks and months after the person seems 
to be well, and the person remains a carrier who can 
spread the disease although he himself is well. The 
germs usually grow in unhealthy tonsils, and are no 
longer found growing when the tonsils are removed by 
an operation. Carriers of diphtheria germs are the 
cause of most cases of diphtheria at the present time. 

Diphtheria in a School. — When diphtheria occurs 
among school children, there is seldom need to close 
the school, or any room in the school (p. 337). If a 
culture is taken from each child in the rooms in which 
cases have occurred, a carrier or two will probably be 
found to be spreading the disease. If the carrier is 
isolated, the other children may safely continue at 
school. 

The Schick Test. — Over half of all persons have 
diphtheria antitoxin in their blood, and will not catch 



PREVENTION OF INFECTIOUS DISEASES 341 


diphtheria when they take its germs into their 
bodies. A test for antitoxin in the blood is that 
called the Schick test, after its discoverer. A physi¬ 
cian makes the test by injecting a very little diphthe¬ 
ria toxin into the skin. If antitoxin is in the blood, 
it destroys the toxin, but if no antitoxin is present, 
the toxin makes a red spot on the skin. If you take 
the Schick test, you can know whether or not you can 
catch diphtheria. 

If there is no antitoxin in the blood, a harmless mix¬ 
ture of toxin and antitoxin injected under the skin will 
act like a vaccine, and will cause the blood to form the 
antitoxin for years afterward. The Schick test and 
the injections of the toxin and antitoxin are given free 
in many cities. 

Scarlet Fever. — Scarlet fever is a dangerous dis¬ 
ease, and yet a child may have it in such a mild form 
that no physician is called, and the disease is not 
recognized. Two or three weeks after the beginning of 
the disease the epidermis begins to peel from the skin 
over all the body. If a person is suddenly taken ill 
with stomach sickness or vomiting, has a sore throat,» 
and the skin on the chest becomes red, the sickness 
may be scarlet fever. If the skin begins to peel after 
two or three weeks, the sickness was almost certainly 
scarlet fever. 

When cases of scarlet fever occur in a school, 
the health officer looks for ,three groups of chil¬ 
dren : 



342 PREVENTION OF INFECTIOUS DISEASES 


1. Those who have sore throat and are beginning to 
be sick. 

2. Those whose skins are peeling as a result of 
having been slightly sick two or three weeks before. 

3. Contacts (p. 330). 

It is necessary to isolate the sick for thirty days from 
the beginning of the sickness, and to watch the con¬ 
tacts during the period of incubation of the disease, 
which is one week or less. 

Some persons suppose there is a difference between 
scarlet fever and what is called scarlet rash, or rose 
rash. These are merely other names for scarlet fever. 
Scarlatina (skar-la-te'na) is the name used for scarlet 
fever in medical books all over the world. 

Measles. —Measles is such a common disease that 
many parents expect their children to have it, and 
take no care to prevent it. The disease is usually 
mild, and yet often produces pneumonia, and causes 
more deaths than scarlet fever. It begins with sneez¬ 
ing and coughing, and running nose and eyes, as if 
the sick person had a cold. After about four days 
the skin begins to break out with red spots. The 
germs are given off from the nose and mouth from the 
beginning of the disease, and the sickness often spreads 
before the sick know that they have measles. It is 
necessary to isolate the sick for ten days from the 
beginning of the sickness, and to watch the con¬ 
tacts during the period of incubation, which is two 
weeks. 



PREVENTION OF INFECTIOUS DISEASES 343 


When measles occurs in a school, the health officer 
looks for two groups of children : 

1. Those who have signs of a cold or the beginning 
of measles. 

2. Contacts who have not had the disease. 

Almost the first sign of measles is a fever. A nurse 

can usually find the cases by taking the temperature 
of every child that appears to be sick. If a child has 
a fever, the place for that child is at home and 
away from other children, no matter what the sickness 
may be. 

Whooping Cough. — Whooping cough is like a cold, 
but the sick person often has a spell of coughing hard 
and long until nearly all the air is blown out of the 
lungs. An inspiration is then taken so suddenly that 
it causes a noisy whoop. The disease often leads to 
pneumonia, and is the cause of about as many deaths 
as scarlet fever; but it is often so mild that there is 
no whooping, and the disease is not recognized. A 
vaccine made of its dead germs is used for preventing 
the disease. 

Typhoid Fever. — Typhoid fever is a disease of the 
intestine. It is often dangerous to life, but may be so 
mild that it produces only a stomach ache and weak¬ 
ness. Its germs leave the body with the excretions of 
the intestine and kidneys. Some persons remain car¬ 
riers of typhoid germs for years after they have re¬ 
covered from the disease. 

The disease is spread by the excretions of the sick or 




344 PREVENTION OF INFECTIOUS DISEASES 

carriers, and by sewage containing the excretions. 
Some of the common routes of infection are: 

1. Fingers soiled with excretions, carrying the germs 
either directly to another person, or to milk and other 
food. 

2. Sewage flowing into drinking water. 

3. Flies alighting on excretions or sewage, and then 
on food. 

Typhoid fever may be prevented in two ways: 

1. By blocking all the routes of infection. 

2. By making the body immune by means of ty¬ 
phoid vaccine (p. 323). 

Typhoid was formerly spread principally by drink¬ 
ing water containing sewage, but cities have now 
blocked that route by proper sewage disposal, and by 
providing pure water supplies. The disease is now 
spread largely by carriers who handle milk and other 
food. When an outbreak of typhoid occurs, a health 
officer looks for a carrier who caused it. 

Hookworm Disease. — In the warmer parts of the 
United States there is a common form of sickness, 
called the hookworm disease , in which there is paleness 
and a great weakness that seems like laziness. The 
disease lasts for years, and is caused by worms about a 
quarter of an inch long which live in the upper part of 
the intestine. The worms suck blood from the mucous 
membrane, and also inject a poison through their bites. 

The route by which the hookworm passes from the 
sick to other persons is as follows: 



PREVENTION OF INFECTIOUS DISEASES 345 

1. The worms lay eggs which pass out of the body 
of the sick person with the excretions of the intestine. 

2. The eggs lie in the soil where they hatch mi¬ 
croscopic worms. 

3. The young worms enter the body by passing 
through the skin of the bare feet of persons who walk 
over the infected soil. 

4. The worms enter the blood stream and pass with 
it to the intestine. 

The disease may be prevented by breaking the route 
of infection at any one of several points: 

1. The worms may be killed in the intestine by 
means of a drug called thymol. 

2. The proper disposal of excretions will prevent 
the eggs from reaching the soil. 

3. Wearing shoes will prevent the young worms 
from entering the skin. 

Diseases of the Air Tubes. — The air tubes from 
the upper part of the nose to the lowest part of the 
lungs form one open space with nothing to shut off one 
part from another. Disease germs which grow in one 
part of the tube may extend to other parts. The germs 
usually enter the body through the nose or throat. If 
they grow only in the nose, the sickness which they pro¬ 
duce is usually called a cold. If the germs extend 
to the throat, the sickness is called a sore throat or ton¬ 
sillitis ; if they reach the air tubes below the throat, 
the sickness is called bronchitis ; and if they grow in the 
air cells, pneumonia. 



346 PREVENTION OF INFECTIOUS DISEASES 



A Common Cold. — There is a common form of 
sickness, called a common cold , or a cold in the head , in 
which there are sneezing and coughing, pains in the 
nose and head, and often sore throat. Its germs are not 

very poisonous, and 
seldom grow below the 
nose and throat, or 
produce a severe ill¬ 
ness. This form of 
sickness is often sup¬ 
posed to be caused by 
exposure to cold and 
wet; but it is infec- 

Bacteria from the Nose of a Person tious and is caused by 
Who has a Bad Cold disease germs whkh 

(Magnified 1000 times.) Nearly all kinds of ... . . 

colds are infectious and may spread from one readily Spread irom 
person to another. one person tQ another 

The disease is usually mild, and those who have it go 
among other persons as usual and spread their germs 
wherever they go. The sickness often comes in waves, 
or epidemics. When one person in a family has it, 
everybody else in the family is likely to catch it; and 
when a few persons catch it, they often give it to 
nearly everybody else in the town. 

Many dangerous diseases are often mistaken for 
common colds. Any mild form of disease of the air 
tubes is often called a cold. Many colds are caused 
by the germs of pneumonia and influenza; and many 
are measles, or scarlet fever, or diphtheria in their early 









PREVENTION OF INFECTIOUS DISEASES 347 

stages or in mild forms. All these diseases, as well as 
common colds, are infectious and may be prevented 
by the same means. 

Colds spread principally by contact of the sick with 
the well. The two principal means of preventing their 
spread are: 

1. The isolation of the sick. 

2, The disposal of the discharges from the noses and 
throats of the sick. 

Colds will be prevented when everybody understands 
what a cold is and is willing to try to prevent its spread. 

Influenza. — A great wave, or epidemic, of a disease 
called influen'za , or the grippe (grip), has swept over 
the world about once in thirty years. The last great 
epidemic began in 1918. The disease occurs in all 
degrees of severity, from a mild cold to a deadly 
pneumonia. It is extremely infectious, and is spread 
principally by contact. When it has appeared, most 
persons who have not had the disease have caught it. 
Few persons catch it the second time, and the disease 
has disappeared after everybody has had it; but it 
has reappeared about thirty years afterward, after the 
time that is needed to raise up a new generation of 
persons who have not had the disease. 

Pneumonia. — Pneumonia is a disease in which the 
germs grow in the lungs and cause the air cells to be¬ 
come filled with liquid or solid matter. Pneumonia 
germs usually grow in the nose and throat for several 
days before they extend down the air tubes and into 



348 PREVENTION OF INFECTIOUS DISEASES 


the air cells. The disease which they produce seems 
like a common cold while the germs are growing in 
the nose and throat; but the sickness becomes worse 
as the germs extend down the air tubes until finally 
it becomes dangerous pneumonia. What is supposed 
to be only a common cold may be caused by pneumonia 
germs, and may be the beginning of pneumonia. 
Many colds are caused by pneumonia germs which do 
not extend below the throat. 

Pneumonia is an infectious disease, and is caught 
from some one who either has the disease, or has a 
cold that is caused by pneumonia germs. The three 
principal means of its prevention are: 

1. Isolation of the sick. 

2. The disposal of excretions from the noses and 
throats of the sick. 

3. Any means which promotes strength and vigor 
of the body, for such means will also promote immu¬ 
nity to pneumonia. 

Immunity to pneumonia germs is lessened by any 
injury or weakness of the body. The pneumonia 
germs may be able to grow only in the nose and throat 
if a person is strong and well. But if that person is 
weakened by fatigue, or by exposure to cold, or by 
drinking alcohol, or by any other means, the pneu¬ 
monia germs which enter the body may extend down 
the air tubes to the lungs. But there will be no pneu¬ 
monia, or even a cold, unless disease germs are pres¬ 
ent to produce it. 


PREVENTION OF INFECTIOUS DISEASES 349 


QUESTIONS 

Why does the law require physicians to report all cases of infectious 
diseases to the health officers? 

What common diseases must be reported? 

How will a health officer find cases which are not reported ? 

What are contacts? Into what two groups are they divided? 

Why does a health officer search for contacts when he is called to a 
case of infectious disease ? 

Why does a health officer inquire particularly about the date of 
onset of a disease? the date of exposure? 

By what four means does a health officer try to prevent the spread 
of an infectious disease ? 

What is quarantine f isolation? 

What care should be given to the excretions from one who has an 
infectious disease? 

What is a disinfection? 

Describe some means of disinfecting excretions; of disinfecting a 
room; of disinfecting clothing and toilet articles. 

Describe some of the means of breaking up the routes by which 
disease germs may be carried. 

How may the body be made immune to a disease? 

Why should a school not be closed when an epidemic occurs in a 
town ? 

Describe diphtheria. How may diphtheria be recognized? How 
.may it be told from tonsillitis? 

Why should a culture be made from every sore throat? 

What three things should be done with every person who has 
diphtheria? 

Why should antitoxin be given ? 

What is a diphtheria carrier ? 

What is the Schick test? 

In what two ways may a person be made immune to diphtheria? 

Describe scarlet fever. 

When scarlet fever occurs in a school, for what three groups of 
children will the health officer search ? 

What signs does a child show at the beginning of measles before the 
skin breaks out? 


350 PREVENTION OF INFECTIOUS DISEASES 


What is the danger from whooping cough ? 

Why should every child who coughs be sent home from school? 

How is typhoid fever spread? 

Describe hookworm disease. 

Describe the route by which the hookworm passes from one person 
to another. 

What diseases may disease germs produce when they grow in the 
air tubes? 

What is meant by the term a common cold ? 

What dangerous diseases are often like colds? 

How are colds spread ? 

How is pneumonia spread ? 

What are the three principal means of preventing pneumonia ? 

For the Teacher. — The object of this chapter is to explain the effective 
methods which a modern health officer uses in preventing the spread of in¬ 
fectious diseases. The influence and opportunities of the teacher in preventing 
infectious diseases are almost as great as those of the health officer and family 
physician. The teacher occupies a position of trust and responsibility in caring 
for the health and welfare of the pupils during several hours of each day. Her 
opportunities for teaching and demonstrating the methods of cooperation of 
the public with the health department are even greater than those of the health 
officer and physician. 

When a case of infectious disease occurs in the school, let the teacher use 
the opportunity to instruct the pupils regarding the methods which are used 
to prevent the spread of the disease. If possible, have the health officer visit 
the school and talk to the pupils. Above all let the teacher insist on keeping 
the school open, and on having the pupils examined every morning by a 
physician or nurse in order to detect every case in its incipiency before it can 
spread infection to others. 

Let the teacher learn from the health officer or physician how to recognize 
the signs of a beginning infectious disease, and the measures to take with the 
pupil who shows the signs of a beginning sickness. A teacher can readily do 
this, and can thus become the most valuable ally that the health officer has. 

Emphasize the need of cooperating with the health officer in finding the dates 
of onset and exposure, and in discovering contacts, and other infected cases. 

Emphasize the fact that while disinfectants and fumigations have some 
value, yet their use is only a beginning of the real work of preventing diseases. 

A teacher can render valuable assistance in keeping track of contacts, or 
those children who have been exposed to cases of infectious disease, and are 
likely to come down with the sickness. 


CHAPTER XXVIII 


TUBERCULOSIS 

Tuberculosis, the Modern Pestilence. — Formerly, 
when little was known about the causes of diseases 
and about their prevention, plagues and pestilences, 
such as smallpox, scarlet fever, and cholera, used to 
sweep over the land and kill large numbers of the in¬ 
habitants each year. We now know how to keep them 
from spreading, and have almost wiped out those dis¬ 
eases which come suddenly and kill quickly. Yet one 
great pestilence is still among us. Tuberculosis, or 
consumption, is a disease which now kills 125,000 per¬ 
sons each year in the United States, or more than the 
number of soldiers who were killed in battle during the 
Civil War. It is often called the great white plague, 
because it is very common among white races, and 
because those who have it become pale, and slowly 
waste away. About one tenth of all deaths in the 
United States are due to it, and yet it may be prevented. 

Bacteria of Tuberculosis. — Tuberculosis is caused 
by a kind of bacteria growing in the body. They 
grow in the lungs more often than in other organs. 
They sometimes grow in the bones or joints, and there 
give rise to forms of hip-joint disease, hunchback, and 


351 



352 


TUBERCULOSIS 


other troubles. They may grow also in the brain, the 
skin, the intestine, and in most other parts of the body. 
Tuberculosis of the lungs is often called consumption. 

Cows may have tuberculosis, and the germs may 
then be found in their milk. The flesh of diseased 
animals may also contain the germs. Government 
inspectors are sent to slaughterhouses to examine the 
animals that are killed, and to destroy meat which 
contains signs of the presence of the germs. 

How Tuberculosis Is Taken. — A person catches 
tuberculosis from some person, or some animal, that 
has the disease. The germs are not given off by the 
breath, or by the sound skin, but the phlegm that is 
spit out from the mouth of the sick contains them. 
Drying and freezing do not kill the bacteria, and when 
they rise as dust, another person may breathe them 
and catch the disease. The germs may be carried to 
food by house flies. The bacteria sometimes enter the 
body through pricks, or cuts, and also by means of 
milk or meat from cattle which have the disease. 

The bacteria do not grow within the body of every 
one who breathes them, for in a strong, healthy body 
the white blood cells destroy them, and substances in 
the blood prevent their growth. But if a great number 
of the bacteria enter the body at one time, the blood 
may be unable to overcome them all. If the body is 
weakened by overwork, or by indigestion, or a cold, 
or other sickness, the bacteria may grow, even though 
only a few enter the body. 



TUBERCULOSIS 


353 


Signs of Tuberculosis. — A person who has tuber¬ 
culosis has little pain and feels but little sickness at 
the beginning of the disease. He usually feels tired, 
loses weight and strength, and often supposes that his 
feelings are due to hard work. He usually coughs as 
if he had a cold. Having a cough for some weeks, and 
losing flesh and strength, are two common signs of 
tuberculosis. 

Another sign of tuberculosis is a fever. A mild 
cold does not usually cause a fever, but if a person who 
seems to have had a cold for some weeks has a fever 
every afternoon, it is likely that he has germs of tuber¬ 
culosis growing in his lungs. 

Scrofula. — Children sometimes have a disease, 
formerly called scrofula , in which the lymph glands 
of the neck become enlarged and form hard swellings. 
The swellings may become red and tender, and may 
contain pus. They are often caused by tuberculosis 
germs which enter the glands through the throat. 
Adenoids and enlarged tonsils are two common throat 
troubles which allow the germs to enter the flesh and 
the glands. If the disease is neglected, it may produce 
tuberculosis of the lungs. 

Tuberculosis of Bones. — A bone or joint that has 
tuberculosis is swollen and tender, and the bone itself 
becomes softened. A bone or joint that slowly be¬ 
comes sore and swollen probably contains the germs of 
tuberculosis. The hip joint is often affected with 
tuberculosis. 


OV. GZN. HYG.-23 




354 


TUBERCULOSIS 



The Main Routes by Which Tuberculosis Is Spread 


How Tuberculosis Germs Are Spread. —• If a person 
has tuberculosis, the principal way by which germs of 
the disease leave the body is in the mucus, or phlegm, 
that is spit from the throat. This mucus is called 
spu'tum. Tuberculous persons usually cough often, 
and spit up a great deal of sputum. Thousands of 
persons who have the disease spit upon public streets 
and the floors of workrooms. The germs become 
dried and float in the air as dust. For this reason the 
dust from city streets, and the air of poorly ventilated 
workrooms usually contain the germs of tuberculosis. 
Those who work day after day in crowded shops are 
almost sure to take germs of tuberculosis into their 
bodies, and these germs are likely to grow if the work¬ 
men are overworked or underfed. 

















TUBERCULOSIS 


355 


Spitting. — Spitting on pavements and on floors is 
one of the principal means of spreading tuberculosis. 
Persons often have tuberculosis without knowing that 
they have the disease, and so it is not safe for any one 
to spit on pavements and floors. Spitting on these 
places is so dangerous that the laws of most states and 
cities forbid it, and signs are posted in cars and public 
places telling of the punishment which may be given 
to those who break the law. 

Disposal of Sputum. — If those who have tubercu¬ 
losis will catch and destroy all their sputum, they may 
safely go among other persons. While they are away 
from home, they may catch the sputum in clean hand¬ 
kerchiefs which they may safely carry in waterproof 
pockets. They may then kill the germs by boiling 
the handkerchiefs when they get home. While the 
sick person is at home, he may catch his sputum in 
paper cups, and burn them at the close of the day. 

Using a spittoon is almost as dangerous as spitting 
on the floor, for a spittoon cannot be cleaned, and flies 
may crawl over it and carry away the disease germs 
to other persons. 

A tuberculous person will sometimes soil his face and 
hands with sputum. Cleanliness of the skin is of 
great importance in preventing the escape of the germs. 

Contact with Tuberculosis. — The most frequent 
way of catching tuberculosis is through direct contact 
with a tuberculous person, as by kissing, sleeping in the 
same bed with the sick, drying the face on the same 




35 6 


TUBERCULOSIS 


towel, and eating from the same dishes. The hus¬ 
bands, wives, and children of the sick are more likely 
to catch the disease than others, for their faces often 
come close to the faces of the sick, and they often use 
the same toilet articles as the sick use. But the 
sick may safely live among their families if they are 
cleanly, have their own toilet articles, and keep their 
faces away from the faces of others who are near 
them (p. 317). 

Protection against Tuberculosis. — There are two 
principal means of preventing tuberculosis: 

1. Preventing its germs from entering the body. 

2. Keeping the body so healthy and strong that the 
germs will not grow if a few should enter it. 

One means of preventing tuberculosis germs from 
entering the body is to guard against coming into 
close contact with a person who has tuberculosis. 
Another way is to avoid those things which may con¬ 
tain the germs, such as public drinking cups (p. 223), 
toilet articles that have been used by other persons, 
impure milk (p. 293), and meat from diseased cattle 

(P- 35 2 )- 

Any means which will make the body strong and 
healthy will also help it to overcome any germs of tuber¬ 
culosis that may enter it. Some of these means are 
deep breathing (p. 135), exercise and rest (p. 87), and 
proper eating (p. 271). 

The germs of tuberculosis often enter the body by 
means of foul and dusty air which is breathed. Foul 


TUBERCULOSIS 


357 


air is also one of the principal causes of weakness and 
poor health. By always breathing pure air, one may 
prevent tuberculosis germs from entering the body, 
and may also help to make the body strong enough 
to overcome the germs. The chapter on ventilation 
is important in connection with the prevention of tu¬ 
berculosis (p. 161). 

Curing Tuberculosis. — Tuberculosis may usually be 
cured if it is treated early. The signs of cured tuber¬ 
culosis may be found in over half of the bodies which 
are examined after death. Many persons get well from 
an illness that they never knew was tuberculosis. 

Four things are necessary in curing tuberculosis: 

1. Fresh air. 

2. Good food. 

3. Rest. 

4. Disposal of sputum. 

Fresh Air. — One of the most important of all things 
in curing tuberculosis is fresh air all the time, day and 
night. The sick must have it even if the air is cold. 
Cold air is not dangerous. It is not even uncomfort¬ 
able if plenty of clothing is worn. In those hospitals 
in which the greatest number of cases get well, the sick 
live out of doors all day, and sleep in porches which are 
wide open to the air and are connected with warm 
dressing rooms. 

Good Food. — Another thing which will help to 
cure a tuberculous person is good food. The sick can¬ 
not build flesh and strength out of medicines, or out of 



358 


TUBERCULOSIS 


anything else except food. They need all the good food 
that they can digest, but no more. Overfeeding is as 
harmful to a consumptive as to a healthy person. The 
sick need meat, eggs, milk, and other foods that may be 
easily digested, and are also rich in protein, for they 
must build new flesh like a child (p. 272). One of the 
best signs of improvement is a gain in weight. 

Rest. — A third thing which tuberculous persons 
need is rest, for they need all their strength to overcome 
the germs of the disease. A little exercise is helpful, 
but the sick must not get tired. 

A great many persons die of tuberculosis because they 
do not stop hard work when they begin to be sick. 
They may safely do as much work as their strength 
will allow without their becoming tired. 

Care of Sputum. — A fourth thing to do in order 
to recover from tuberculosis is to destroy the germs in 
the sputum. A person may start the germs growing 
in new parts of the lungs, or flesh, by taking them back 
into the body. Many fail to get well because they are 
uncleanly and do not take care of their sputum. Sun¬ 
shine in the room, and cleanliness of the floors and 
furniture, are also necessary in order to kill all the 
germs that are in the sick room. 

Teaching about Tuberculosis. — One of the most 
important steps in both the prevention and the cure of 
the disease is to teach all persons about it, in order that 
they may support sanatoriums and hospitals for its cure 
and provide proper housing and working conditions for 



TUBERCULOSIS 


359 


the prevention of the disease. Many cities and states 
have societies which send out printed instructions about 
tuberculosis. Some states have exhibitions of charts, 
pictures, and models, showing how the disease may be 
prevented and cured. 

Sanatoriums. — Many cities and counties have hos¬ 
pitals and sanatoriums for the care of persons who have 
tuberculosis. One of the most valuable uses of these 
places is to teach the sick how to breathe, how to eat, 
how to exercise, and how to live in the best way to get 
well and stay healthy. 

QUESTIONS 

Why is tuberculosis called the great white plague? 

Out of every one hundred deaths in the United States how many are 
caused by tuberculosis ? 

What is the cause of tuberculosis? 

If a person has tuberculosis of the lungs, from what part of the 
body does he give off the germs of the disease ? 

How do tuberculosis germs usually enter the body of a well person? 

What are some of the first signs that appear when a person has 
tuberculosis ? 

What is scrofula? 

How are tuberculosis germs usually spread ? 

What harm is done by spitting on pavements and floors? 

How can a person who has tuberculosis destroy the germs in his 
sputum? 

How may the germs of tuberculosis be prevented from entering the 
body? 

How may the germs of tuberculosis be prevented from growing 
after they have entered the body ? 

Of what use is fresh air in curing tuberculosis? 

How much food does a person who has tuberculosis need to eat? 

Of what use is rest in the cure of tuberculosis? 



3 6o 


TUBERCULOSIS 


Why is the destruction of the sputum necessary in curing a person 
of tuberculosis? 

Give some reasons why every person should learn about the pre¬ 
vention and cure of tuberculosis. 

For the Teacher. — Refer to the subject of poor nutrition in Chapter XXII. 
Tuberculosis is a common cause of poor nutrition, and, on the other hand, 
poor nutrition is usually one of the earliest signs of beginning tuberculosis. 

Nearly every person receives a few germs of tuberculosis into the lungs at 
some time during childhood ; but the body usually overcomes the germs so that 
they give no sign of their presence. It may be that a few germs of tuberculosis 
in the body act as a vaccine and cause the body to form protective substances 
which prevent the growth of germs which enter the body later. 

Emphasize the fact that proper correction of the three causes of poor 
nutrition which are mentioned on page 271 will usually enable the body to 
overcome the germs of tuberculosis which may be in the body. 

The measures which are used to cure tuberculosis are those which enable 
a well person to keep his body strong and vigorous. 

A child who is in the earliest stage of tuberculosis is not a menace to others 
and may be allowed in school, for he seldom gives off the germs of his disease 
until he has a cough. But any coughing child should be excluded from school, 
for he will give off the germs of the disease which is causing the cough. 

A child who has a fever should be sent home and put to bed for his own 
sake, whether he has tuberculosis or not. Fever is always a sign of serious 
illness, and rest in bed is a necessary part of its treatment. 


CHAPTER XXIX 


THE NERVOUS SYSTEM 

I 

Need of a Nervous System. —- Every part of the 
body must have help from other parts in order to live. 
The arm cannot live unless it receives blood from the 
heart, food from the stomach, and oxygen from the 
lungs ; and it can¬ 
not work unless 
it receives orders 
from the brain. 

Each organ must 
help all the rest 
of the body, and 
so it must receive 
directions telling 
it when to act, and 
how much to do. 

The work of direct¬ 
ing the actions of 
the different organs of the body is done by the organs of 
the central nervous system. 

Central Nervous System. — The principal organs 
of the central nervous system are the brain and the 
spi'nal cord. The brain fills the top of the skull above 
the eyes and ears. The spinal cord is about as large 

361 



The Brain, Side View 
(4 natural size.) 




362 


THE NERVOUS SYSTEM 


around as a little finger. It hangs inside of the back¬ 
bone, and extends from the brain about to the waist¬ 
line. The brain and the spinal cord 
are almost as soft as jelly; but they 
are protected from injury by the 
heavy bones of the skull and the 
backbone. 

Nerves. — The brain and spinal 
cord are connected with all the other 
organs of the body by threads of 
flesh called n'crves. Twelve pairs of 
nerves are joined to the lower part 
of the brain, and thirty-one pairs 
to the spinal cord. The use of nerves 
is to carry messages between the or¬ 
gans of the body and the central nerv¬ 
ous system. 

Nerves are like telephone wires. 
The stomach, lungs, muscles, skin, 
and all other parts of the body are 
like customers who have telephones 
in their houses. The brain and spinal 
cord are like central telephone sta¬ 
tions which the customers call up 
natural size.) The when they wish to send messages. 

Nerves do not run directly from one 
organ to another, but nearly all mes¬ 
sages between the organs pass through either the 
spinal cord or the brain. 



The Spinal Cord 


jstrings at the sides arc 
the beginnings of 
nerves. 







THE NERVOUS SYSTEM 


363 


Nerve Cells. — The parts of the brain and spinal 
cord that receive and send messages are called nerve 
cells. The nerve cells are so small that they cannot 
be seen without a microscope. They have small 
bodies and long branching arms. Some of these 
branches are the nerves which go to all parts of the 
body. Other branches of the cells extend to other 
nerve cells. The nerve cells are like the operators 
in a central telephone station. Their use is to receive 
and to send messages which pass between the dif¬ 
ferent parts of the body. 

The brain and the 
cord consist of 
nerve cells and nerves. 

That part which contains 
nerve cells is reddish gray 
in color, and is called gray 
matter. That part of the 
brain and spinal cord 
which consists of nerves 
is white in color, and is 
called white matter. Gray 
matter covers the outer 
part of the brain, but 
it forms the central part 
of the spinal cord. 

Motor Nerve Messages. — Most of the messages 
which nerve cells send out are orders to do some¬ 
thing. Any nerve which carries messages away from 




Nerve Cells from the Brain 

(Magnified 200 times.) A nerve is a pro¬ 
longation of one of the branches of a nerve 

cell. 






3 6 4 


THE NERVOUS SYSTEM 


the central nervous system is called a motor nerve. 
There are four principal kinds of motor nerve mes¬ 
sages : 



i. Some of the motor messages are orders for the 
cells all over the body to take food and grow. When 

a muscle is exercised, it 
grows large, because the 
spinal cord sends orders 
for it to take a large 
quantity of food from 
the blood in order to 
do its work well. 

2. Some of the motor 
messages are orders for 
the glands to secrete 
their liquids. When the 
stomach receives food, 
the spinal cord sends 
orders for the glands to manufacture gastric juice. 

3. Some of the motor messages are orders for the 
involuntary muscles to contract. When cold air 
strikes the skin, the spinal cord sends orders for the 
muscles of the arteries to contract, so as to keep the 
blood away from the skin. 

4. Some of the motor messages are orders for volun¬ 
tary muscles to contract (p. 84). Every motion of 
a muscle is ordered by the nerve cells. If no orders 
reach the muscles, a person cannot move, and we say 
that he is paralyzed . 


A Nerve Cut Across 

(Magnified ioo times.) A nerve is like a 
telephone cable containing many nerve fibers. 




THE NERVOUS SYSTEM 


365 


Sensory Nerve Messages. — The messages which 
the organs send to the brain and spinal cord are called 
sensory nerve messages, because many of them pro¬ 
duce feelings or sensations. One class of sensory mes¬ 
sages are those by which the organs tell of their need 
of food, or oxygen, or rest. After hard exercise the 
feeling of shortness of breath is the message by which 
the muscles tell the brain of their need of oxygen. If 
it were not for the sensory nerve messages, the brain 
and spinal cord would not know what orders to send 
to the various organs. 

Other messages that the organs of the body send to 
the brain are those telling about things which are out¬ 
side of the body. These messages are sensations of 
touch, sight, hearing, smelling, and tasting, and are 
called th e five senses. 

If something which is touching the body harms it, 
the feeling which is produced is one of pain in the in¬ 
jured spot. Pain is often a useful feeling, for it gives 
warning of danger to the body. 

Conscious Nerve Actions. — Nerve actions may be 
divided into two classes: first, those which can be 
felt, called conscious nerve actions; and second, those 
which cannot be felt, called unconscious nerve actions. 

We are usually conscious of only two kinds of nerve 
actions: first, the motor messages to the voluntary 
muscles; and second, the sensory messages which the 
brain receives through the five senses. Nearly all 
other nerve messages are sent and received without our 


366 


THE NERVOUS SYSTEM 


knowledge. For example, we are usually conscious of 
sending orders for the movements of our arms and legs, 
and receiving messages of sight and hearing; but we 
are not conscious of the messages which order the flow 
of gastric juice, or of the messages by which the muscles 
tell of their need of food. The number of unconscious 
nerve actions is far greater than those of which we are 
conscious. 

The nerve messages of which we are conscious are 
either received by, or are sent from, the nerve cells of 
the gray matter in the upper part of the brain. We 
therefore say that the upper part of the brain is the 
seat of consciousness , and of the mind. These cells 
do the work of thinking, and send out the orders for 
voluntary movements. 

Unconscious Nerve Actions. — The messages which 
control the acts of secretion and growth, and the move¬ 
ments of the involuntary muscles, are either received 
by, or are sent out from, the nerve cells in the spinal 
cord and in the lower part of the brain. These actions 
are not under the control of the mind; they go on 
whether a person thinks about them or not, and whether 
he is asleep or awake. 

When the nerve cells of the upper part of the brain 
are injured, as by a blow on the top of the head, a per¬ 
son is unconscious, like one in a deep sleep. But life, 
growth, and repair of the body may still go on if the 
nerve cells of the spinal cord and lower part of the brain 
are in good order. 



THE NERVOUS SYSTEM 


367 


Relation of Brain and Spinal Cord. — The gray mat¬ 
ter of the upper part of the brain is like a man who 
drives an automobile, but does not repair the car or 
keep it in order. The work which 
the driver does is like the conscious 
work of the brain. 

The gray matter of the lower 
part of the brain, and that of the 
spinal cord, is like a workman who 
sees that the car is repaired and 
kept in good order, but does not run 
the car. The work which the re¬ 
pair man does is like the uncon¬ 
scious work of the spinal cord and 
the brain. 

The Spinal Cord and Voluntary 
Movements. — The cells of the 
spinal cord and of the lower part 
of the brain usually act only in 
answer to messages which they re- diagram of a Nerve 
ceive from some other part of the Mess y EE . ^ oxi )^ lun ' 
body. Some of the messages telling a> nerve ceils in the think- 
them to act come from the nerve 
cells of the upper part of the brain. nerve ceils in the motor 

part of the brain; c, nerve 

When a person wishes to move a cell in the spinal cord; 

r i • l • t d, nerve which carries a 

muscle, the cells of his brain send message to a muscle of the 
an order to the cells of the spinal hand ' 

cord, and they repeat the message to the muscles. 

Reflex Action. — The cells of the spinal cord and 








3 68 


THE NERVOUS SYSTEM 


brain often send out orders in answer to sensory messages 
which they receive from the organs of the body. 
When a person pricks his finger with a tack, the 
finger sends a sensory message of pain which passes 
through the spinal cord on its way to the brain. The 



Diagram of a Nerve Message in Reflex Action 

a, a tack pricking the hand; b, nerve carrying a message of the prick to the spinal 
cord; c, nerve cell in the spinal cord; d, nerve carrying a motor message to a 
muscle ordering it to snatch the hand away from the tack. 

cells of the spinal cord at once reply to the message 
by ordering the muscles of the arm to take the hand 
away from the tack, and the finger is already snatched 
away from danger by the time the message of pain 
reaches the brain. 

The action of the brain and spinal cord in sending 
a motor nerve message as a result of a sensory mes¬ 
sage is called re'flex action , because the sensory mes¬ 
sage seems to be reflected, or turned back, as a motor 
message. 

Nearly all the messages for secretion and growth, 
and for movements of involuntary muscles, are reflex 
messages. For example, the cells of the spinal cord 
do not send orders for the stomach glands to produce 










THE NERVOUS SYSTEM 


369 


gastric j uice until they receive word that food is on its 
way to the stomach. They order the arteries of the 
skin to contract when they get a message that some¬ 
thing cold is touching the skin. 

Sympathetic Nervous System. — The spinal cord 
does a great deal of its work with the assistance of sets 
of nerve cells called ganglia (gang'gli-a). The principal 
ganglia are arranged in a double row of twenty-three 
pairs down the whole length of the backbone. They 
are about the size of grains of wheat or oats, and are 
connected with the spinal cord by means of nerves. 
Other nerves go from them to the arteries, and to the 
organs of digestion, respiration, and excretion. The 
ganglia and their nerves form what is called the sympa¬ 
thetic nervous system. 

The ganglia send orders to the organs to do those 
kinds of work which go on slowly and steadily, such 
as the contraction of the arteries, the peristalsis of the 
stomach and intestine, and the secretion of saliva and 
gastric juice. They have very little nerve power of 
their own, but they get most of their power from the 
spinal cord. The spinal cord itself acts in a quick 
and forcible way, as in its reflex action when the finger 
touches a tack. The ganglia slow down the messages 
of the spinal cord and send them out in a gentle and 
continuous stream. For this reason the actions on 
which life depends, such as digestion, circulation, and 
excretion, go on slowly and regularly, and are not 
readily disturbed. 


OV. GEN. HYG. — 24 


370 


THE NERVOUS SYSTEM 


A disorder of any part of the body affects other 
parts through the sympathetic nervous system. For 
example, those who have eye troubles often suffer with 
headaches and stomach sickness. Adenoids in the 
throat interfere with the growth and strength of the 
whole body, even though they do not produce pain 
or a feeling of sickness. A weakness of any part of the 
body may prevent other parts from being strong. 

QUESTIONS 

Why does a person need a nervous system? 

What are the principal organs of the nervous system ? 

Where is the brain situated? 

WTere is the spinal cord situated ? 

Where are nerves found? 

Compare nerves with telephone wires. 

What are nerve cells? 

Where are nerve cells found? 

Of what is the gray matter in the central nervous system composed ? 
the white matter? 

What are motor nerves? 

What are some of the messages that are carried by motor nerves ? 

What are sensory nerves? 

What are some of the messages that are carried by sensory nerves? 

What are conscious nerve messages? 

Name some nerve messages of which a person is conscious. 

Name some unconscious nerve messages. 

What is reflex nerve action? 

Explain the nerve action which takes place when a person snatches 
his hand away after pricking his finger with a tack. 

W’hat part does the spinal cord take in conscious nerve acts? 

Where is the sympathetic nervous system found ? 

Of what does the sympathetic nervous system consist ? 

Over what actions does the sympathetic nervous system have 
control ? 


THE NERVOUS SYSTEM 


37 1 


Where does the sympathetic nervous system get its power to act? 
Why does a disorder of a single organ affect the whole body ? 

For the Teacher. — The object of this chapter is to present the subject of 
the nervous system in a simple, practical way, and in outline only. It is 
scientifically correct to compare the nervous system with a telephone system. 
The comparison is a great help in enabling the pupils to understand the nervous 
system. 

A little comparative anatomy will be an additional help in understanding 
the nervous system. The lower forms of animals, such as worms, have nerves 
and nerve cells, but all the cells are grouped in a row of ganglia of the sympa¬ 
thetic system. Man has the same sympathetic system, and its action is about 
the same as that of a worm, for a man eats, digests food, grows, and carries 
on his other life-sustaining actions in about the same way that a worm does. 

A fish has an excellent sympathetic system and spinal cord, but its brain 
is small and rudimentary. But that part of the brain which is used in seeing 
is as fully developed as the same part of a brain in man, for most fish can see 
well. 

As we pass upward through the various grades of animals from the lowest 
to the highest, we find that additional brain substance is added according to 
the intelligence of the animal. A dog, for example, has well-developed brain 
parts which have to do with its senses and muscular movements, but the think¬ 
ing parts of its brain are small. In man the uppermost or thinking parts of 
the brain are so large that they overlap all the rest; but those parts which 
are concerned with the senses and movements are scarcely larger than they 
are in a dog. 


CHAPTER XXX 


THE BRAIN 

The Three Parts of the Brain. — The part of the 

central nervous system which is inside of the skull is 
called the brain. The greater part of the brain is a 

large mass which 
fills almost all the 
space under the 
rounded top of 
the skull. This 
part is called the 
cerebrum (ser'e- 
brum). Under its 
hinder end is a 
smaller mass 
called the cere¬ 
bellum. 

A slender stem 
of nerve matter from the cerebrum and cerebellum 
extends downward, and is continued outside of the 
skull into the backbone. The part of the nerve stem 
which lies inside of the skull is called the medul'la. 
That part of the stem which lies outside of the skull 
is the spinal cord. 



Human Brain, Underside View 

(■|- natural size.) a, cerebrum; b, cerebellum; 
c, medulla. 


372 







THE BRAIN 


373 


The brain, spinal cord, and nerves may be compared 
to a tree. The spinal cord and the medulla are like 
the tree trunk. The nerves which go from the spinal 
cord to all parts of the body are like the roots of the 
tree. The cerebellum and cerebrum are like the 
rounded top of the tree. 

The Medulla. — A person’s medulla is about as wide 
and half as long as his little finger. Nerves extend 
from it to all parts of the head and neck, just as nerves 
from the spinal cord extend to all other parts of the body. 

The white matter of the medulla consists of nerve 
threads which join the cerebrum and cerebellum to 
the spinal cord. Some of the nerve cells of the gray 
matter of the medulla control the motions of the mus¬ 
cles of the head and neck, and other cells have some 
control over the heart. 

A small group of nerve cells which lie near the center 
of the medulla within a space about the size of a pea 
have control over the movements of breathing. If 
these cells were destroyed, breathing would stop at 
once, and death would occur almost instantly. This 
part of the medulla is sometimes called the seat of life. 

The Cerebellum. — The cerebellum is about the 
size of a large hen’s egg. Its outer part consists of 
gray matter whose cells control the movements of the 
muscles in balancing the body, as in standing or run¬ 
ning. The cells also cause the muscles of the body to 
act in a regular and orderly manner in making a num¬ 
ber of quick and exact motions, as in playing a piano. 


374 


THE BRAIN 


The Cerebrum. — The cerebrum is about five times 
as large as all the rest of the central nervous system 

put together. It 
covers the rest of 
the brain, and is 
the only part which 
is seen when the 
rounded top of the 
skull is removed. 
It consists of gray 
matter covering a 
central mass of 
white matter. The 
cells of the gray 
matter are the seat 
of the mind, and of 
conscious nerve ac¬ 
tion (p. 365). The 
white matter con¬ 
sists of nerve threads 
which connect the 
nerve cells with each 
other and with the 
rest of the body. 

The surface of the 
cerebrum is folded 
and crumpled, and 
looks as if its cov¬ 
ering of gray matter 



Human Brain, Top View 
(\ natural size.) All that can be seen is cerebrum. 


"V * 


"■v 




* ' i teffr 

■W \ r 


Human Brain, Cut in Two Crosswise 

natural size.) a , white matter of cerebrum; 
b, gray matter of cerebrum; c, cerebellum; 
d, medulla. 








THE BRAIN 


375 


were too large for it. Because of the folding, the 
amount of gray matter is about three times as much 
as it would be if the brain were smooth. A child is 
bom with a very few folds on its brain, but as its 
mind grows, the folds on its cerebrum also grow in 
number and size. 

The Work of the Mind. — The mind acts by means 
of the nerve cells of the cerebrum. These cells do three 
kinds of work: first, 
they receive sensory 
messages by means of 
the five senses (p. 365) ; 
second, they send out 
motor messages to the 
voluntary muscles; 
and third, they think. 

Each part of the 
brain has one kind of 
work to do. The cells 
in the part of the 
cerebrum behind the 
ears receive messages 
through the five senses. 

Those just above and 
in front of the ears send out orders for moving the vol¬ 
untary muscles. Those in the front part of the cere¬ 
brum do most of the work which is called thinking. 

Memory and Thinking. — The nerve cells of the 
cerebrum keep a record of the messages which they 



Diagram of the Action of the Dif¬ 
ferent Parts of the Brain 




376 


THE BRAIN 


receive and send out. This record is called the mem¬ 
ory », and the messages which are recorded in it form a 
person’s knowledge. 

A person can look over the messages which he has 
stored in his memory. He can compare them with one 
another and in this way he can get new knowledge. 
This work of the mind is called thinking. 

Training the Mind. — The nerve cells of the cere¬ 
brum have many branching arms which extend to the 
nerve cells in other parts of the brain. By means of 
these branches a nerve cell knows what other cells are 
doing. 

Brain cells and their branches grow by use, just as 
muscles grow by exercise. The brain cells of a baby 
are small, and their branches are few and short, but the 
branches grow in number and length as the child’s 
mind grows. Your muscles and bones will stop grow¬ 
ing when you are about twenty-five years old, but 
your brain cells may grow until you are about fifty 
years old, if you exercise your mind and train it. 

When you stop studying and thinking, your brain 
cells stop growing. If you leave school when you are 
fifteen years old, and do not study or think hard after 
that age, your brain cells will also stop growing, and you 
will always have the mind of a fifteen-year-old child. 
But if you study, and read, and think, your brain cells 
and your mind will keep on growing for many years 
after your bones and muscles are full-grown. 

When you read a book about a bell or other object, 


THE BRAIN 


377 


you use the nerve cells which think. When you see a 
bell, or hear it, you also train the nerve cells which re¬ 
ceive messages from the eyes and ears; and when you 
ring a bell, you train the nerve cells which send motor 
messages to your hands. Thus you may train your 
mind by seeing and hearing, and by working with 
your hands, as well as by reading. 

Most mental training at school consists in teaching 
the thinking cells which lie just behind the forehead. 
But you will not be educated unless the cells by which 
you send motor messages, see, and hear, also receive 
training. 

Laboratory work in school, and working in a car¬ 
penter shop, are as much a part of mind training as 
studying a book or listening to a speech. A boy who 
has been trained only from books at school or college 
has to start work in a low position in a shop or store in 
order to train that part of his brain which was not 
trained at school. But the boy who has trained his 
forehead cells to think will soon be able to train the 
rest of his brain. 

Habits. — When you recall anything to memory, the 
cells of your brain try to do the same thing that they 
did when they formed that memory. When you think 
about a flower, the cells which receive messages of sight 
recall the messages which they have received about 
the color of the flower, and you can seem to see the 
flower again even when you close your eyes. When 
you recall an act to memory, the cells which sent out 


378 


THE BRAIN 


the orders from the brain when the act was done want 
to send out the orders again when you think of 
the act. 

After your brain cells have done an act a few times, 
they often try to repeat the act, whether you wish them 
to do so or not. We then say that you have a habit of 
doing that act. Every person forms habits in his work 
and play. Some persons form habits of always getting 
up early, eating properly, acting politely, and speaking 
pleasantly. All these are good habits. 

Forming Good Habits. — You form most of your 
habits while you are young. The good habits which 
you form will be as lasting as the bad ones. Every 
one forms habits in his eating, dressing, speak¬ 
ing, thinking, sleeping, walking, and in doing all the 
other acts of everyday life. All these habits have an 
effect on the health of the body. For example, the 
things which a person eats, and the way in which he 
eats them, are among the principal things which affect 
health. Yet most grown persons eat in the way in 
which they formed habits of eating while they were 
young. Those whose eating habits are right seldom 
have indigestion or stomach troubles. 

You will easily fall into bad habits if you are careless 
and do not think about your actions. Some boys and 
girls think they can do a forbidden thing a few times 
without forming a habit of doing it. There is danger 
in doing any wrong or improper act, for by repeating the 
act you will do it more and more readily until you will 


THE BRAIN 


379 


do it without thinking. Do not begin to do a wrong 
or improper act at all. 

You can overcome a bad habit if you put a right 
habit in its place. The cells of your brain will slowly 
forget what is stored in memory if you do not recall it 
to mind. If you wish to overcome a bad habit, watch 
yourself and do the act in the proper way. Your brain 
cells will then forget the wrong way of doing the act, 
and you will form a habit of acting properly. 

Habits of Mental Health. — It is your duty to form 
wholesome habits of thought. You can form the habit 
of thinking good of a person instead of evil; of being 
cheerful instead of glum and morose, truthful instead 
of deceitful, patient instead of irritable, courageous in¬ 
stead of fearful, kind instead of hard-hearted, indus¬ 
trious instead of lazy, and cooperative instead of selfish. 
These and similar habits of thought will make you 
pleasing to others, and will help you to be successful 
in life. 

Mental Habits and Social Relations. — The respect 
which your fellows and companions show to you will 
depend on the respect and consideration which you 
show to them. Your success in holding a position will 
depend on how well you please your employer, not only 
by your good work, but also by your good manners and 
the respect which you show to others. Good manners 
and courtesy are the result of good mental habits. A 
gentleman has the habit of showing respect to those in 
authority, obedience to the law, consideration to his 



380 


THE BRAIN 


parents and other members of his family, and courtesy 
to all. He is willing to assume the obligations of cit¬ 
izenship, and to give service to society in return for the 
benefits which he receives from the public. 

Directing the Thoughts. — You can turn your 
thoughts to anything you wish, but your mind can do 
only one thing at a time, and do it well. When you 
try to do an arithmetic example, you forget your work 
if you look out of the window, or listen to a noise, or 
whisper to some one. If you have a hard example to 
do, you can do it best if you keep your whole mind on 
the work until you finish it. 

You can compel your mind to think of a single sub¬ 
ject for many minutes or hours. A studious pupil will 
not notice the sounds and sights around him, and will 
forget his feelings of hunger and thirst while he is get¬ 
ting his lessons. Every person who has a strong mind 
has the power to keep his whole thought on a single 
thing for hours at a time. One of the principal things 
which you learn at school is how to think without being 
disturbed by what goes on around you. 

Nervousness. — If a person cannot keep his mind 
on a single thing at a time, but is easily disturbed by 
what goes on around him, we say that he is nervous. 
Some persons suppose that what is called nervousness 
is a sign of a strong mind, because those who are nerv¬ 
ous often take notice of slight feelings, sounds, and 
sights which most persons do not notice. No person 
can think well if he allows himself to be disturbed by 



THE BRAIN 381 

what he feels, or hears, or sees. Nervousness is not 
a help, but it is a great hindrance to thinking. 

Many persons are nervous and irritable because 
they have not been taught habits of self-control. 
Some children are nervous because they are not 
trained to behave, and to put their minds to their work. 
Others are nervous because they really have something 
the matter with their bodies. Those who are sick, or 
tired, or in pain, are nervous because they do not feel 
well. The sickness gives them about all the unpleas¬ 
ant feelings that they can stand, and if an unpleasant 
sight or sound is added to their feelings, they become 
cross and fretful. A child who has a stopped-up nose, 
and has to breathe through his mouth, is likely to be 
cross and fretful, for he always has an uncomfortable 
feeling, and any discomfort added to that makes more 
than the child can stand. 

Other common causes of nervousness in children are 
sitting up late at night, indigestion, improper eating, 
adenoids, and foul air. These things are also causes of 
ill health. Doing the things which make the body 
healthy and strong will often prevent or cure nerv¬ 
ousness. 

Joy of Health and Strength. — A person who is 
healthy will have very few feelings which make him 
think about his body. He will be able to use his arms, 
and legs, and all the rest of his body as he would a 
machine which is in perfect order. Almost the only 
uncomfortable feelings that he will have will be 


382 


THE BRAIN 


hunger, thirst, weariness after work, and other feelings 
which tell him what his body needs. He will work 
hard for the pleasure of working, and will put forth his 
strength for the delight of using it. Children and 
young animals play until they are tired out, because 
the use of their strength is a joy to them. 

A healthy grown person will enjoy life like a child. 
He will not notice the slight aches and pains which 
come while he works and plays, but he will enjoy trying 
his endurance and strength. Even his hunger and his 
tired feelings will not be unpleasant, for his eating, 
his rest, and his sleep will be among the greatest pleas¬ 
ures of the day. 

Tired Nerve Cells. — When nerve cells work, they 
use up some of their own substance, as muscle cells do 
when they act. After a few hours of work they shrink 
in size and become unable to go on with their work. 
There is then a tired feeling like that which comes after 
muscular work. Nerve cells direct the actions of the 
muscles, and doing muscular work tires the brain as 
well as the muscles. Many of the tired feelings after 
exercise are due to tired nerve cells. 

When a person thinks about a single thing day after 
day, the nerve cells which are in use do not get time to 
rest. A pupil who thinks about his examinations 
for hours and days does not allow his brain cells to rest, 
and he comes to his test tired out. A person who 
worries wears out his brain cells by thinking about his 
troubles during every moment. Any one who sticks 


THE BRAIN 


383 


closely to only one kind of work without resting will 
finally ruin his health, for nerve cells need to rest and 
to store up food just as muscles need rest. 

Rest for Nerve Cells. — A good form of rest for nerve 
cells is a change of work, for it brings a different set of 
nerve cells into use, and allows the tired cells to rest. 
A boy who studies hard all day will get brain rest by 
playing baseball after school, for his thinking cells will 
rest while he uses the nerve cells with which he directs 
his muscles. A bookkeeper who sits at a desk all day 
may get brain rest by tending a garden, or driving, or 
taking photographs. A tired business man will rest his 
brain while he drives an automobile for an hour or two 
at the close of the day. 

If a person has no liking for play or pleasure, his 
mind will always be thinking about his work, and the 
nerve cells with which he does his work will get no rest. 
It is a good thing for every person to learn to like some 
kind of play or pleasure, for during playtime the work¬ 
ing cells of the brain will rest. 

Sleep. — The mind gets a complete rest during sleep, 
for then the nerve cells of the cerebrum seem to lose 
their connection with the rest of the body. But the 
spinal cord and the medulla act as perfectly while a 
person is asleep as while he is awake. The object of 
sleep is to allow the nerve cells of the cerebrum to re¬ 
pair their worn-out parts and take a new supply of 
food. 

Every person must have sleep. He can go without 


3^4 


THE BRAIN 


food longer than he can go without sleep. One of the 
first signs of danger from overworking the mind is 
trouble in sleeping. This is because the nerve cells 
have formed such a habit of working every moment 
that they cannot stop working when the person lies 
down at night. 

Muscular relaxation is necessary for mental rest and 
sleep (p. 89). A person who is nervous or restless 
usually has some of his muscles contracted, because 
the motor cells of his brain are as active as the think¬ 
ing cells. Practicing complete muscular relaxation is 
a great help in causing sleep. 

While the brain is at work, a large quantity of blood 
flows through it, but during sleep it contains only a 
little blood. One of the principal things which pre¬ 
vent sleep is too much blood in the brain. When you 
cannot fall asleep, you can often hear your pulse 
in the ear which lies on the pillow. Anything which 
will cause the blood to leave your brain will help you to 
fall asleep. Soaking your feet in hot water will cause 
the blood to flow to your feet and away from your brain. 
Eating a light lunch will cause the blood to flow to your 
stomach. Having some one rub your back will cause 
the blood to flow to the muscles of your back. Listen¬ 
ing to some one reading a dull book will keep you from 
thinking about your work, and the blood will then 
leave your brain, and you will feel drowsy. These 
are some simple things which will help you to fall 
asleep. 


THE BRAIN 


385 


Mental Defects. — Some persons have brains that 
do not act properly on account of injury or disease. 
These are persons of unsound mind, and include the 
feeble-minded , the mentally infirm, and the insane. 

The Feeble-Minded. — The minds of many children 
stop developing at too early an age. The mental age 
of a feeble-minded person is the age at which a normal 
person has the mental development of the one who is 
defective. A person who has the mind of a one-year- 
old baby is called an idiot; of a four-year-old child, an 
imbecile; and of a child from five to fourteen years 
old, a moron. The mental age of a backward child can 
be determined by an examination, or mental test, sim¬ 
ilar to that by which a teacher determines the proper 
grade to which a pupil belongs. 

Many backward children are bright in certain sub¬ 
jects. Some have great talents for music, and others 
for making things with their hands. Many schools 
have special classes in which backward children are 
trained for earning their living. 

The Mentally Infirm. — The brain, like a muscle, 
loses its power in old age. Those who are mentally 
infirm on account of age, and who have no means of 
support, are given care in almshouses. 

The Insane.— An insane person can usually do 
most mental acts in a proper way, but he is likely to 
act disorderly and to injure himself and others; and 
so he requires care and watching. 

Many persons with disordered brains would not 

OV. GEN. HYG. — 25 



386 


THE BRAIN 


have become insane if they had not overworked their 
brains. After constant worry or weeks of work upon 
a single object, the brain may be unable to change 
its thoughts or direct them to other objects. A person 
with such a brain is insane. Vacations, and play be¬ 
tween the hours of work, would prevent many persons 
from becoming insane. 

Care of the Insane. — If a person has an injured 
arm, the principal thing to do for it is to give it entire 
rest until it can grow strong again. The principal 
thing to do for an insane person is to prevent his brain 
from doing those acts which it cannot do properly. 
This can be done in the best way by taking the person 
away from his home and his work, and placing him in 
a hospital where new thoughts will fill his mind. Most 
insane persons improve, and many recover, within a 
few weeks or months after they enter a hospital. 

Alcohol and the Brain. — One of the principal effects 
of alcohol on the body is to poison the nerve cells of the 
brain. This is what is meant when it is said that drink 
goes to the head. The most common form of the 
poisoning is drunkenness (p. 61). 

When a person drinks, the first nerve cells to be 
poisoned are those with which thinking is done. One 
of the first signs that a man is getting drunk is that he 
talks without thinking how his words sound. This 
poisoning begins soon after the alcohol is taken. 

The next brain cells to be poisoned are those by 
which the muscles are moved. In this stage of drunk- 



THE BRAIN 387 

enness a person cannot walk straight or talk 
clearly. 

The next brain cells to be poisoned are those by 
which messages are received through the senses. The 
drunken person then knows nothing, but lies as if in a 
deep sleep. The alcohol may also poison the cells in 
the lower part of the brain, and life is then in danger, 
for these cells control the breathing and the heart. 

In olden times men used to have contests to see 
who could drink the most liquor. It was thought 
that the winner would be the coolest and most thought¬ 
ful person in times of accident or danger, for if alcohol 
did not upset his thoughts, it was supposed that noth¬ 
ing else would upset them. The alcohol often dulled 
his mind and thoughts, and the drinker would then 
perform daring acts. The reason why alcohol seemed to 
make men brave and cool was not that it helped them 
to think, but that it kept them from thinking 
clearly. 

If alcohol really made men brave and thoughtful, 
it would be given to firemen when they go to dangerous 
fires. But one of the strictest rules in all fire depart¬ 
ments is that the men shall not drink, for the kind of 
thoughtless daring produced by alcohol is dangerous 
both to the firemen themselves and to those whom they 
would try to save. 

Effects of Light Drinking. — After the brain cells 
have been slightly injured over and over again, they 
cannot recover from the harm. Taking alcoholic 



3 88 


THE BRAIN 


liquors injures the mind, even though not enough al¬ 
cohol is taken at any one time to produce drunkenness. 
The first signs that a drinker is harmed are usually 
shown by his carelessness in his work. Drinkers lose 
their keenness of judgment, and often make mistakes 
in their work. If a drinker were the cashier of a bank, 
he would be likely to add columns of figures wrong. 
Railroad managers will not allow a drinking man to 
have anything to do with running trains. 

Alcohol and Poverty. — The use of alcohol often 
makes men poor. They lose good positions because 
they are not able to do their work well. They spend 
their money for drink instead of for food, and 
clothes, and houses. A place where the effects of 
drinking may be seen is an almshouse, where poor 
persons who are too weak to work are supported at 
public expense. 

! Alcohol and Crime. — Another place where the 
effects of drinking may be seen is a prison. Many 
criminals take whisky to make themselves daring ' 
enough to commit their crimes. Others commit crimes 
because the drink takes away their thoughts and pre¬ 
vents them from seeing the evil of their acts. Al¬ 
cohol has long been regarded as one of the great causes 
of crime. 

Alcohol and Insanity. — A third place where the 
effects of steady drinking may be seen is a hospital 
for the insane. Alcoholic drink is a common cause of 
insanity. Many insane persons are the children of 




THE BRAIN 389 

drinking parents, and were born with weak minds be¬ 
cause'of their parents’ drinking. 

Cigarettes and the Mind. — The use of tobacco hin¬ 
ders the growth of the cells of the brain. Tobacco is 
a narcotic to the nerve cells of both the old and the 
young, but it is a far worse poison to young persons 
than to grown persons, because it prevents the nerve 
cells from growing. Very few boys who smoke ciga¬ 
rettes stand well in their classes at school. Nearly 
all boy criminals use cigarettes. Most of the idle boys 
who stand on street corners are cigarette smokers. 

QUESTIONS 

Into what three parts is the brain divided ? 

What is the size and shape of the medulla? 

What is the use of the medulla ? 

Why is the medulla sometimes called the seat of life? 

Where is the cerebellum situated? 

What is the use of the cerebellum ? 

Where is the cerebrum situated? 

What is the size of the cerebrum ? 

Where is the gray matter of the cerebrum? 

Of what use are the folds on the surface of the cerebrum? 

What part of the brain does the conscious work of the mind ? 

What are the three principal kinds of work which are done by the 
nerve cells of the cerebrum ? 

In what part of the cerebrum are the nerve cells with which a 
person feels, sees, and hears? 

In what part of the cerebrum are the nerve cells which send orders 
to the voluntary muscles? 

What is memory? 

What takes place in the brain when a person thinks? 

In what part of the cerebrum are the nerve cells with which thinking 
is done? 



390 


THE BRAIN 


What happens to nerve cells when the mind is trained? 

What is a habit f 

How are good habits formed ? 

How may bad habits be overcome ? 

What is nervousness? 

What are some of the causes of nervousness? 

How do tired nerve cells differ in appearance from rested cells? 

How does a change of work help to rest nerve cells? 

What makes nerve cells tired during muscular exercise? 

Of what value is play to a business man? 

What is the use of sleep? 

What are some of the reasons why a person sometimes cannot fall 
asleep when he lies down at night ? 

What are some of the things which will help a person to fall asleep ? 

What effect does light drinking have on a person’s mind ? 

What effect does drinking have on a person’s getting employment ? 

What effect does drinking have on a person’s power to earn money? 

What effect does drinking have in causing crime? 

What effect does drinking have in producing insanity? 

What effect does tobacco have on the brain cells of young persons? 

For the Teacher. —The object of this chapter is to explain the simplest 
elements of the physical basis of mental action. The work of the medulla is 
almost like that of the spinal cord ; and that of the cerebellum is the coordina¬ 
tion of muscular movements. The distinctive work of the cerebrum is that of 
carrying on conscious mental actions. 

The principle underlying the elementary actions of the cerebrum is that 
of the localization of brain actions. In a general way the three elementary 
divisions of mental actions are the sensory, the motor, and that of thought. 
The motor area of the brain is definitely mapped out, but the sensory area is 
less definitely known. While most of the front part of the brain is con¬ 
cerned in thought, yet all parts are connected in an intricate way, and the 
processes of thought enter into the actions of the motor and sensory areas. 
This explains why training the muscles and the organs of special sense is ex¬ 
cellent mental training. 

Brain cells may be trained to act in as certain a manner as muscle cells, and 
they are subject to the same disorders that affect the cells of other parts of the 
body. Practical applications of these principles are given under the topics 
of habits, mental concentration, brain fatigue, and perverted mental action. 


CHAPTER XXXI 


THE SENSES 

Use of the Senses. — The principal nerve messages 
of which a person is conscious are those which are 
received through the senses (p. 365). They consist 
of messages of touch, smell, taste, hearing, and sight. 
Their principal uses are to give the mind a knowledge 
of what goes on outside of the body, and to warn a 
person about his safety and comfort. 

Touch. — The sense of touch is produced by the 
pressure of objects upon nerves that lie just beneath 
the epidermis of the skin (p. 189). If the epidermis 
is removed, anything that touches the bare spot pro¬ 
duces a feeling of pain or smarting. 

The sense of touch gives the mind a knowledge of 
the size, shape, hardness, smoothness, weight, and 
warmth of objects which touch the skin. The parts of 
the body in which the sense of touch is the keenest are 
the ends of the fingers and the tip of the tongue. 

One way of testing the sense of touch is to press upon 

the skin on different parts of the body with the sharp 

points of a pair of compasses. The skin of the back 

will seem to feel only a single point if the tips of the 

compasses are separated two inches. The ends of the 

391 



392 


THE SENSES 


fingers can feel that the points are separated if the 
points are only one eighth of an inch apart. 

Weight. — A person judges the weight of an object 
in two ways : first, by the feeling of touch and pressure 
which the object gives when he holds it in his hand; 
and second, by the feeling which he has in his muscles 
when he lifts it. 

Use of Pain. — Pain is a useful sensation because it 
is a message that some part of the body is in danger. 
If you could not feel pain, you might be seriously in¬ 
jured or even be killed before you knew of the danger. 
The pain of a decaying tooth will drive you to a den¬ 
tist for relief, but an abscess along the root of a tooth 
often gives no pain, while its poisons may spread 
through the body and produce heart disease before you 
are aware of the tooth trouble. 

False Messages. — The nerves of feeling go from the 
skin to the spinal cord, and then to the brain. If a 
nerve is wounded anywhere in its length, the feeling 
seems to be at its outer end, and not at the place where 
it is hurt. What is called the funny bone is a nerve 
which lies just above the inner side of the tip of the 
elbow. If it is pinched at the elbow, there is a feeling 
of pricking and smarting in the little finger where the 
nerve starts. 

If a person sits with the legs hanging down from the 
edge of a chair, the feet often tingle and feel heavy 
and “ asleep,” because the nerves which go from them 
to the spinal cord are pinched at the knee. At 


THE SENSES 


393 


the beginning of hip-joint disease the pain is usually 
felt in the knee, and in appendicitis the pain often 
seems to be over all the lower part of the body. The 
part in which a pain is felt is not always the part which 
is out of order. 

Training the Sense of Touch. — You can train the 
sense of touch by use. Surgeons train their finger 
tips in the examination of parts which lie deep in the 
body. Blind persons learn to read by passing their 
finger tips over raised letters. When you train your 
sense of touch, you train the nerves under the skin to 
receive slight impressions. You also train the cells 
of your brain to recognize slight differences in the mes¬ 
sages which they receive. Training the sense of touch 
is excellent mental training. 

Smell. — Tiny bits of matter are always passing into 
the air from everything which has an odor. When 
these bits of matter touch the nerves of the nose, 
they give rise to a message which the brain receives as 
a smell. By means of the sense of smell a person can 
judge of the purity of food and air. Dogs, and some 
other lower animals which have a keen sense of smell, 
depend upon it as much as persons depend upon the 
sense of sight. 

Taste. — When a substance which has a taste is 
taken into the mouth, some of it dissolves in the saliva 
and soaks through the epidermis. When it touches the 
nerves of the tongue, it gives rise to a message which 
the brain cells receive as a taste. The sense of taste 


394 


THE SENSES 


enables a person to judge something about the purity 
and wholesomeness of food. The taste of food also has 
a great effect on the flow of gastric juice, and on the 
digestion of food (p. 263). 

A person judges the tastes of sweetness and sourness 
by means of the nerves in the front part of the tongue. 
He judges bitterness and saltness by means of the 
nerves in the back part of the tongue. He judges the 
taste of spices largely by means of particles which rise 
to the nose and there produce an odor. A person who 
has a cold in the nose loses a part of his sense of taste, 
because of the hindrance to his sense of smell. 

Hearing. — One way in which a person learns about 
objects which do not touch the body is by means of 
air waves which are set in motion by the objects when 
they vibrate rapidly. These air waves, striking the 
nerves of the ear, produce the messages which the brain 
receives as sounds. Loud sounds are caused by strong 
air waves which are sometimes felt with the nerves 
of the skin, but the only waves which are heard are 
those which strike the nerves of the ears. 

The Ears. — The ear consists of three parts, called 
the outer ear, the middle ear, and the inner ear. 

The outer ear consists of two parts: first, the shell, 
which is usually called the ear; and second, a tube 
which extends from the shell of the ear about an inch 
into the side of the head. The bottom of this tube is 
closed by a thin sheet of flesh, called the eardrum , which 
is like the head of a drum. 



THE SENSES 


395 


A space called the middle ear is hollowed, out of hard 
bone behind the eardrum. The middle ear is filled 



Photograph of the Inner Parts of the Human Ear 

(Natural size.) They are surrounded by solid bone which has been cut away below 
the dotted line, a, eardrum ; b, bones of middle ear; c, inner ear. 

with air, and contains a chain of three small bones 
extending across it from the eardrum to a smaller 
drumhead on the opposite side. 

A small space called the inner ear is hollowed out 
of the hard bone behind the inner drumhead. The 
inner ear is shaped like a snail shell and is filled with 
a liquid in which the nerves of hearing lie. 

How a Sound Is Heard. — Air waves strike the ear¬ 
drum, and cause it to move back and forth. This 
moves the bones of the middle ear, and they produce 
waves in the liquid of the inner ear which strike the 
nerves of hearing. The nerves carry a message of the 
motion to the brain, and the brain cells receive the 
message as a sound. 









39 <> 


THE SENSES 


Deafness. — If a person cannot hear well, we say 
that he is deaf. Deafness is nearly always caused by 
some trouble in the middle ear. 

A tube called the Eustachian (u-sta'ki-an) tube ex¬ 
tends from the middle ear to the throat. If you hold 
your nostrils closed, and try to blow hard, you will 



force air into the middle ear. You will then feel a 
buzzing in your ear, and will not be able to hear well, 
for the pressure of the air will keep the eardrum from 
moving freely. When you swallow, you open the tube 
and let the air out of the middle ear, and you can then 
hear well again. 

Most deafness is caused by throat trouble which 
stops up the Eustachian tube. For this reason ade- 













THE SENSES 


397 


noids are often the cause of deafness. Most children 
who are deaf have adenoids, and the removal of the 
adenoids will nearly always help their hearing (p. 143). 

Running Ears. — Sometimes a soreness and swelling 
in the throat extend up the Eustachian tube into the 
ear. The ear then becomes filled with a thick liquid, 
like that which is coughed from the throat. This 
liquid presses upon the eardrum and causes an earache. 
If the drum bursts, the pain will stop as soon as the 
matter runs out. But some matter will often keep on 
running from the ear for days and weeks afterward. 

A child who has earache and running ears is nearly 
always deaf. Most of these children may be made 
well, and their deafness cured, by a skillful physician. 

Testing the Hearing. — Many children seem to be 
dull and careless at school because they are slightly 
deaf and do not hear what is said to them. In many 
schools the hearing of every pupil is regularly tested. 

A good way to test a person’s hearing is to stand 
about ten feet away from him and whisper numbers for 
him to repeat. In this way you can find out how loud 
a sound he can understand. Test each ear separately 
while the other ear is closed. 

A person with good hearing will be able to under¬ 
stand a loud whisper in a quiet room about twenty-five 
feet away from his ear. If he can understand a loud 
whisper no farther away than five feet, his hearing is 
only one fifth as good as it should be. It is a good plan 
for a person with good hearing to stand beside the one 




39 ^ 


THE SENSES 


whom you are testing, so as to compare the hearing 
of the two. 

Training the Hearing. — Most sounds are made up 
of many separate sounds. The sound of the music 
made by a singing class is made by a number of persons, 
and a trained musician can pick out the sound of each 
separate voice. The same sounds fall upon the ears 
of all who listen to the music, but the trained person 
will notice differences between sounds which seem alike 
to untrained persons. Training the ears is really train¬ 
ing the brain to notice slight differences in the messages 
which the ears send to the brain. 

Injuries to the Ears. — The middle ear and the inner 
ear are hollow spaces deep in a hard bone of the skull, 
and are seldom injured except by blows which injure 
the whole skull. Almost the only way by which one is 
likely to injure an ear is to thrust something against 
the eardrum. Picking the ears in a careless way, or 
putting things into the outer ear in fun, may injure 
the eardrum. Slapping or boxing the ears may also 
injure the eardrum by producing a sudden pressure of 
air upon it. 

Earwax. —■ A brown wax is formed by the skin which 
lines the outer half of the tube of the outer ear. The 
use of Ihe wax is to protect the lining of the outer ear. 
The epithelium of the skin grows outward and carries 
the wax with it, and there is seldom need to pick the 
wax from the ears. If it should collect, it may be re¬ 
moved safely by means of the loop of a fine wire hairpin. 





THE SENSES 


399 


QUESTIONS 

What are the senses ? Of what use are they ? 

In what part of the body is the sense of touch produced ? 

In what part of the skin is this sense the keenest? How can you 
test its keenness? 

What sense do blind persons use when they read ? 

How do you judge the weight of an object? 

Explain the unpleasant feeling which you have in your little finger 
when you pinch your funny bone. 

Explain the feeling which you have in your foot when it is “ asleep.” 
How is the sense of smell produced ? Of what use is it ? 

How is the sense of taste produced ? Of what use is it ? 

What kinds of taste do you judge with the front part of your tongue? 
with its back part? 

How does the sense of smell help you to judge the taste of an object ? 
How does a bell or other object produce a sound? 

Of what does the outer ear consist? 

What are the principal parts of the middle ear? of the inner ear? 
How does sound travel from the outer ear to the nerves of hearing? 
What is the Eustachian tube? 

How does throat trouble produce deafness? 

How do adenoids produce earache? 

How can you test the hearing of a person ? 

How does brain training help the hearing? 

How may slapping the ears injure the hearing? 

How may earwax be removed from the ears with safety? 


For the Teacher. — Children are often heedless and inattentive because 
they are partly deaf and neither they nor their parents are aware of the defect. 
Test the hearing of every pupil in the room, and pay special attention to those 
who are even slightly deaf. 

If a child has a running ear or other form of ear trouble, try to get his 
parents to secure the proper treatment for him, for he is not likely to “ outgrow ” 
the defect. Many forms of deafness may be improved or cured by proper 
treatment. 

Emphasize the object of pain, and the necessity of heeding its warning, by go¬ 
ing to a physician in order to have its cause determined and removed. 


CHAPTER XXXII 


THE EYE 

Importance of Sight. — The principal way by which 
we learn about an object which is beyond the reach 
of our hands is by means of light which comes from it 
to our eyes. Few persons could carry on their daily 
work if their sight were suddenly taken away. 

The Eyeball. — The framework of the eye is a thick 
and tough shell called the eyeball . The eyeball is 
shaped like a hollow globe, and is filled with a clear 
liquid. It is white, except its front part, which is clear 
like glass, and is called the cornea (kor'ne-a). 

The Iris. — The eyeball has a dark-colored lining, 
called the choroid (ko'roid) coat , which is about as 
thick as writing paper. The front part of this lining 
hangs like a curtain behind the cornea, and is called the 
iris (i'rfs). The color of the iris is usually some shade 
of blue or brown. It shows through the cornea, and 
gives the eye its blue or brown color. 

The Pupil. — In the center of the iris there is a round 
hole, called the pupil , through which light enters the 
eye. The pupil appears black because the inside of 
the eye is dark in color. The iris contains muscles 


400 





THE EYE 


401 



...CORNEA 
IRIS 


LENS 


NERVES 
OF SIGHT 


which regulate the size of the pupil. A strong light 
causes the muscles of the iris to contract and make the 
pupil small in order to shut out some of the light. 
When the light is dim, the muscles relax and the pupil 
becomes large so as to admit as much light as possible. 
The pupil of a cat’s 
eye is only a narrow 
slit in the daytime, 
but at night it is a 
large, round hole 
which admits much 
more light than the 
pupil of a person’s 
eye. For this reason Diagram of the Eye 

a cat can see at night better than a person. 

The Lens. — A rounded piece of tough flesh, called 
the lens , lies just behind the pupil. It is as clear as 
glass, and its front and back faces are curved like the 
faces of a small magnifying glass. Its use is to bend 
rays of light in such a way that they come together 
upon the back of the eyeball, and there form a picture 
of objects which are in front of the eye. 

The Retina. — A large nerve called the optic nerve 
enters the back part of the eyeball and spreads over 
the choroid coat. This coating of nerves is called the 
ret'ina. When light falls upon the retina, its nerves 
carry a message of sight to the brain. 

The Eye Like a Camera. — An eye is like a pho¬ 
tographer’s camera. The eyeball is like the camera 

OV. GEN. HYG. — 26 











402 


THE EYE 


box. The choroid coat is like the black paint with 
which the inside of the camera is coated. The cornea 
and the lens are like a double lens in the camera. The 
retina is like the plate on which the picture is formed. 

Focusing the Eye. — When a photographer takes a 
picture, he moves the lens back and forth until the 
image is distinct upon the back part of the camera. 
If the image of a distant object is distinct, the image 
of an object near the camera will be blurred. Ad¬ 
justing a camera to make a distinct image of an ob¬ 
ject is called focusing . 

The eye is naturally focused to form a distinct image 
of an object which is over twenty feet away. When a 
person looks at an object which is nearer than twenty 
feet, muscles inside the eyeball make the lens more 
curving or bulging, in order to form a distinct image 
upon the retina. 

Reading often tires the eyes, because the muscles 
of the eyes have to act upon the lens in order to form 
clear images of the print. When your eyes become 
tired from study, you may rest them by looking at the 
view from a window, for the muscles which focus your 
eyes are at rest while you look at distant objects. 

Blurred Sight. — A person who has good sight can 
focus his eyes to see an object which is only six inches 
away. Some persons can see distant objects clearly, 
but their eye muscles are unable to make the lens curv¬ 
ing enough to see objects close by. These persons are 
called farsighted. The lenses of their eyes are not suffi- 



THE EYE 


403 


ciently curved. Most persons become farsighted after 
they pass the age of forty years. 

Some persons cannot see distant objects clearly, but 
have good sight for objects which are held only a few 
inches from their eyes. These persons are called near¬ 
sighted. The lenses of their eyes are too curving. 

Sometimes the lens or the cornea is not perfectly 
curved, but is irregular in shape. Objects then appear 
blurred. This trouble is called astig'matism. 

Use of Spectacles. — Farsightedness, nearsighted¬ 
ness, and astigmatism may all be helped by the use 
of spectacles, for the roundness of the glasses will cor¬ 
rect the faults in the roundness of the lenses of the eyes. 
Proper glasses will not harm the eyes in any way, but 
they will strengthen the eyes, and will keep the sight 
from failing. Going without glasses when they are 
needed is often a cause of weak eyes and headaches. 

Spectacles that are held in place by bows over the 
ears are more comfortable than eyeglasses that are held 
in place by springs fastened to the nose. If children 
wear eyeglasses, the pressure of the springs may hinder 
the growth of the bones of their noses. 

No one can see well through dirty glasses. If you 
have to wear glasses, keep them clean. 

If the spectacles are set crooked on the nose, the 
eyes will ache from trying to look through them. If 
they will not stay in place squarely in front of the 
eyes, bend their frames or bows so that they will lit 
the eyes. 



404 


THE EYE 


Cross-eyed Sight. — The eyeball may be turned 
or rolled in every direction by means of six muscles. 
The eye must be turned directly toward an object in 
order to see it clearly. If a person’s two eyes are not 
turned equally toward an object, two images of the 
object will be seen. The person is then said to see 
double, and to be cross-eyed. 

Some persons have double sight only when their eyes 
are tired. Slight forms of double sight are often the 
cause of severe headaches. Cross-eyed sight and the 
headaches resulting from it may be relieved by a good 
oculist. 

Signs of Poor Sight. — Many persons have poor 
sight and do not know it. Many children seem to be 
dull at school because they cannot see well. Many 
children are born with poor sight, and no one finds it 
out until the children go to school. 

One of the principal signs of poor sight is a headache 
which comes on after using the eyes. The cause of the 
headache is a pain in the muscles of the eyes. 

Another sign of poor sight is a blurring of the sight 
after the eyes are used for some time. The cause 
of the blurring is the tiredness of the eye muscles from 
the constant strain of focusing or turning the eyes. 

Testing the Sight. — Cards for testing the sight may 
be obtained at most jewelry stores. They bear large 
letters of various sizes clearly printed on cardboard. 
Test a person’s eyes by placing one of the cards about 
twenty feet away, and have him read as many of the 




THE EYE 


405 


letters as he can. The following table gives the dis¬ 
tances at which a person with good sight should be 
able to read letters of various sizes. 


Height of 

Distance at which 

letter 

it may be read 

3-J inches 

200 feet 

if inches 

100 feet 

if inches 

70 feet 

inch 

50 feet 

-J inch 

40 feet 

f inch 

30 feet 

■| inch 

2c feet 


A person’s sight may 
be recorded in the form 
of a fraction in which 
the numerator is the dis¬ 
tance of the person from 
the card, and the de¬ 
nominator is the dis¬ 
tance at which the 
smallest letters which he 
reads should be read by 
a person with good sight. 
For example: If a per¬ 
son stands 20 feet from 



Testing the Eyesight 


Cover one eye while testing the other. 

a card, and the smallest 

letters which he can read are f inch high, he sees 
only f-g-, or \ as well as a person who has good sight. 

If your sight is not good, go to an oculist and let him 
test your sight and fit you with glasses. Most persons 












406 


THE EYE 



who have poor sight are able to see well when they 
wear the right kind of spectacles. 

How the Sight Is Injured. — Many children are born 
with an eye weakness which becomes worse after strain¬ 
ing the eyes and using them improperly. The most 
common causes of harming the eyes are a wrong light 
and a wrong position in reading or working. 


Reading by Lamplight 

Sit with your left side toward the light. Hold your book squarely in front 

of your face. 

Wrong Lighting. — A bright light shining into the eyes 
causes their muscles to contract so as to shut out the 
light. The muscles constantly pulling upon the eyeballs 
may press them out of shape and cause blurred sight. 









THE EYE 


407 


Reading in a dim light tires the muscles of the eyes, 
for when the sight is not good, the muscles keep trying 
to focus the lenses. A light is of the proper strength 
when it is agreeable to your eyes. 

The best position for the light is at your left side, for 
it then does not shine into your eyes, and your right 
hand does not shade your work. 

Improper Position in Reading. — When you look 
directly forward, the muscles which move your eyes 
are at rest. When you turn your eyes up, or down, or 
sidewise, the muscles flatten the eyeball as they pull 
upon it, and prevent you from seeing distinctly. When 
you read, place your book squarely in front of your 
face in order that your eye muscles may have as little 
work to do as possible. When you study at a table, 
have the top of your book raised, in order that the 
pages may lie squarely before your eyes while you sit 
upright. 

Reading while lying down tires your eyes, for you 
then have to turn your eyes downward toward your 
feet. When you read on a railroad train, your book 
shakes, and your muscles soon become tired in keeping 
your eyes turned toward the page. 

Injuries to the Eye. — The eye is set deep in a bony 
socket which protects it from blows. It lies upon a bed 
of fat which acts like a spring and allows it to slip about 
when it is jarred or struck. The outer shell of the eye¬ 
ball is as thick and tough as sole leather, and can 
scarcely be cut with a sharp knife. An eye is seldom 


408 


THE EYE 


injured by accident except by shot or by sharp instru¬ 
ments which strike it directly in front. 

Sometimes the skin around the eye is made purple 
or black by blows over the eye. The color is seldom in 
the eye itself, but is in the bruised skin around the eye. 

Dirt in the Eye. — The eye is covered with two mov¬ 
able lids which protect it from dust and slight injuries. 
The surface of the eye is moistened with a fluid, called 
tears , which is produced by a gland lying just above the 
eyeball. 

The eye is very tender, and becomes painful when 
there is a speck of hard dirt between the lids and the 
eyeball. If you have a bit of dirt under an eyelid, do 
not rub the eye, for the rubbing makes the dirt scratch 
the eye. Grasp the eyelashes, and hold the lid away 
from your eyeball for a moment. The tears may then 
wash the dirt away. If the dirt does not come away, 
let a friend lift the eyelid and brush the dirt away with 
the corner of a clean handkerchief. 

Sore Eyes. — The most common cause of sore eyes 
is the growth of disease germs under the eye¬ 
lids and on the eyeball. The germs make the eyes 
red, and cause them to smart and to ache. Many 
kinds of eye diseases are infectious, and are caught 
from other persons who have sore eyes. 

Do not use a towel or handkerchief which has been 
soiled by any one with sore eyes. If you have sore 
eyes, use your own towels and handkerchiefs, and boil 
them when they are washed. You can help to cure 




THE EYE 


409 


sore eyes by washing them often with warm water so 
as to remove the germs. 

The eyes of babies are often injured by house flies 
crawling over them. Drive the flies from the room 
where a baby is to sleep, or cover it with mosquito 
netting in order to prevent flies from crawling over 
its face. 

One form of sore is called granulated lids , or trachoma 
(tra-ko'ma). It is very infectious, and is becoming 
common in some places. If it is not properly treated, 
it becomes worse and worse, and often destroys the 
sight. But it may readily be cured by a doctor. 

Training the Eye. — When you look at an object, 
images of everything in front of your eyes are formed 
on their retinas, but the brain takes notice of only the 
images which you wish to see. For example, if you 
look at a bird in a tree, images of the bird, the tree, 
and the sky are all formed in your eyes, but your brain 
takes notice of the image of the bird only. 

When you look carefully at an object, the thing which 
you wish to see is often the dimmest and most blurred 
part of the object. You can train your brain to notice 
and recognize dim and blurred images that scarcely 
make an impression on the eye at all. For example, 
a sailor, seeing a dim speck miles away on the water, 
can tell whether or not it is a ship, and what kind of 
vessel it is. Training the eyes is really brain training. 
Any person who has fair sight can train his brain to see 
things which an untrained brain will not notice at all. 


4 io 


THE EYE 


Tobacco and the Eyes. — Tobacco sometimes in¬ 
jures the nerves of the eyes, and produces blindness. 
Smoking is more likely to injure the eyes than the use 
of tobacco in any other form. The blindness usually 
passes off when the use of the tobacco is stopped. 

QUESTIONS 

Describe the eyeball, and name its principal parts. 

Of what use is the iris? 

Of what use is the lens? 

In what respect is the eye like a photographer’s camera ? 

How is the eye focused ? 

What is farsightedness f 
What is nearsightedness f 
What is astigmatism? 

How do spectacles help the sight ? 

Why are spectacles with bows more healthful than eyeglasses 
that pinch the nose? 

What is the cause of double sight ? 

What are some of the signs of poor sight ? 

How does poor sight cause a headache ? 

How can you test the sight? 

How does a wrong light injure the eyes? 

How does reading on a railroad train tire the eyes? 

What position of the body and arrangement of the light are the most 
comfortable for the eyes? 

How is the eye protected from injury? 

Of what use are tears? 

Why is it harmful to rub an eye when there is a speck of dirt in it ? 
How can you remove dirt from under an eyelid ? 

Name some ways in which soreness of the eyes may be spread from 
one person to another. 

What is trachoma? 

How can you train your eyes to see faint and indistinct objects? 
What effect does tobacco have upon the sight ? 



THE EYE 


411 

For the Teacher. — It is scientifically correct to compare the eye with a 
camera. 

The most common eye defect is that of the lens. Most forms of lens trouble 
may be corrected by the use of the proper glasses. Many persons object to 
wearing them because they say that when a person begins to wear them his 
sight becomes worse after he leaves them off. It often happens that a person 
who has always had blurred vision first fully realizes his defect when he loses 
his glasses and is compelled to see things blurred again. 

Focusing the lens and directing the eye toward objects are muscular actions. 
Fatigued eye muscles are often the cause of headaches in persons who have to 
put forth considerable effort to see clearly. Test the sight of every pupil 
that has frequent headaches. 

A teacher who has no standard test card can test the vision by the following 
method: Take a newspaper having type of various sizes and place it in a good 
light. Place yourself and the pupil to be tested about three feet in front of the 
paper and have the pupil pronounce letters, beginning with the largest. See 
if the pupil can recognize letters which are as small as those which you can read. 

Try to influence the parents of children with defective vision to secure the 
proper glasses for their children or treatment for them. 

Some forms of soreness of the eyes are contagious, some are caused by un¬ 
clean habits, and some by eyestrain. It is always proper to advise children 
with sore eyes to cleanse them twice a day with warm water in which borax 
is dissolved. If the cleansing does not improve them in a few days, try to 
have the parents secure medical treatment. 


CHAPTER XXXIII 


THE VOICE 

Vocal Cords. — The sound of the voice is made in a 
box, called the lar'ynx (lar'ingks), which forms the up¬ 
permost part of the windpipe. The front upper corner 
of this box forms the lump called the Adam’s Apple, 
which may be felt in the front of the neck just below 
the chin. 

Two white bands of flesh, called vocal cords , are tightly 

Cords open and at rest 

Diagram of 

stretched backward across the top of the larynx. 
When the cords are tightened and brought close to¬ 
gether, and air is forced between them, they tremble 
back and forth and make a sound in the same way 
that blowing through a tin horn produces a noise. 
The sound made by the vocal cords alone is unpleas¬ 
ant and squeaking, but it is increased in power and 

412 



Cords closed and in action 
Vocal Cords ( b ) 




THE VOICE 


4 i 3 


made pleasant by means of the nose, mouth, tongue, 
and teeth. 

Speech. — When a sound is made in the throat, the 
lips, teeth, and tongue may change the air current in 
such a way as to form the sounds of letters and words. 
You form the sound of B by starting with your lips 
closed, and suddenly forcing them open with a blast of 
air which passes through the vocal cords. You form 
the sound of D by starting with the tip of the tongue 
against the front part of the roof of the mouth. When 
you whisper, you do not use the vocal cords at all, but 
make use of the sound produced by blowing air through 
the lips. 

Speech Defects. — Some boys and girls who do not 
pronounce their words plainly suppose there is some¬ 
thing wrong with their lips or tongue. This is almost 
never so. The reason why they do not talk distinctly 
is because they have not learned to move their lips and 
tongue correctly. They can learn to speak distinctly 
if they will notice the correct positions of the tongue 
and lips in pronouncing difficult words, and will then 
practice speaking the words clearly. 

A person who cannot talk is said to be dumb. A 
baby learns to talk by hearing the speech of other per¬ 
sons. The reason why dumb persons cannot talk is 
that they are deaf and do not know what words sound 
like. There is seldom anything the matter with their 
noses and throats, and they learn to talk when they 
are shown how to place their lips and tongues in order 


414 


THE VOICE 


to form words. Children who are totally deaf soon 
learn to talk when they are sent to a school for the deaf 
and dumb. 

Stammering and stuttering are usually the result 
of nervous affections and may be prevented or cured by 
patient training in pronouncing words, and in reading 
and speaking. 



Singing Is a Good Form of Exercise for the Voice 


Exercising the Voice. — The sound of the voice is 
formed by means of muscles. If boys and girls do not 
use their voice muscles, they will grow up with weak 
voices, and will be unable to sing or speak with strong 
tones, or for many minutes at a time. 

You can make your voice muscles strong by exer¬ 
cising them, just as you make the muscles of your arm 
strong by use. A good form of voice exercise is to 
read aloud at home in the evening. 

If you use your voice muscles until they are over¬ 
tired, you will make them weak, just as overworking 


THE VOICE 


4 i 5 


your arm muscles will make them weak. Some of the 
ways in which boys and girls are liable to injure their 
voice muscles are by loud shouting, singing for a long 
time, and long cheering at games. 

A young boy’s voice sounds like a girl’s voice, 
but at about the age of fifteen his larynx suddenly 
grows faster than his body. This growth produces a 
change in his voice, by which it becomes low-pitched 
and deep, like a man’s voice. While this change is 
taking place, the voice muscles may be strained more 
easily than at any other time. 

A Pleasing Tone of Voice. — You like to hear some 
persons talk, because their words sound like music. 
The voices of others are loud, or shrill, or whining, or 
have some other unpleasant tone that makes you feel 
uncomfortable. A voice with an unpleasant tone 
keeps you from resting and increases your discomfort 
when you are sick. The tone of voice with which you 
usually speak will have a great effect upon the health 
and comfort of others. 

You can form a habit of speaking with a pleasing 
tone if you try to do so. To speak always in a pleasant 
and distinct tone of voice is one of the most pleasing 
habits that you can form. 

QUESTIONS 

Where is the sound of the voice made? 

Describe the larynx. 

How do the vocal cords produce sound ? 

What organs do you use when you pronounce letters and words? 


416 


THE VOICE 


How do you form the sound of B? of D? 

How can you improve the distinctness of your speech? 

What is the cause of dumbness ? 

How may a deaf and dumb person be taught to speak ? 

Name some ways in which the tone of the voice may affect a 
person’s health. 

How can you exercise the voice? 

Name some ways in which the voice may be strained. 

What causes the change of voice in boys? What is this change? 

For the Teacher. — Defects of speech are seldom due to tongue-tie, or other 
defect in the mouth, but they are usually the result of careless habits of pro¬ 
nouncing words. Speech is made by muscular action, and some persons have 
lazy habits of speech just as they have of posture and the performance of other 
acts involving the use of muscles. 

The tone of one’s voice has a great effect on the comfort of other persons. 
No one likes to hear a voice that is loud, harsh, or shrill, but the habit of speak¬ 
ing in low-pitched, pleasing tones can be easily acquired. 


GLOSSARY 


Absor'bent cotton, sheets of cotton, free from oil and dirt, and espe¬ 
cially prepared for dressing wounds. 

Absorption, the taking of food from the intestine by the blood. 

Ace'tic acid, the sour substance in vinegar. 

Ad'enoids, soft growths of flesh in the back part of the throat behind 
the nose. 

Adulteration, the mixing of a cheap substance with a valuable one 
in order that the mixture may closely imitate the valuable sub¬ 
stance. 

Al'cohol, a colorless liquid used in manufacturing. It is the intoxi¬ 
cating element in beer, wine, whisky, and other strong drinks. 

Al'ga, one of the simplest kinds of plants. 

Amtno acid, digested protein. 

Anat'omy, the study of the structure of the body. 

Antitox'in, a substance that will destroy the poisons which are pro¬ 
duced by disease germs in the body. Antitoxins for diphtheria 
and lockjaw are in common use. 

An'trum, the hollow space in the upper jawbone. 

Aor'ta, the artery which carries blood away from the left side of the 
heart. 

Ar'tery, a blood tube that carries blood from the heart. 

Artificial respira'tion, making air pass into and out of the lungs in 
imitation of natural breathing. 

Assimila'tion, making food into a part of the body, or putting food 
to use in the body. 

Astig'matism, an unevenness of the surface of the cornea causing 
blurred sight. 

Au'ricles, the two thin-walled cavities on the upper end of the heart. 

Bacte'ria, the smallest known plants. Some cause decay, and others * 
produce diseases. 

Balanced diet, a bill of fare which supplies the body with the proper 
food substances. 

Bandage, a dressing wrapped around a wounded part. 

Bi'ceps, the muscle that lies on the front of the upper arm and bends 
the elbow. 

Board of health, a body of officers who have charge of matters per¬ 
taining to public health. 

OV. GEN. HYG. 27 


417 


418 GLOSSARY 

• 

Bot'ulism, a dangerous form of poisoning caused by eating spoiled 
canned food. 

Bron'chi, the air tubes of the lungs. 

Caffeine, the stimulating substance in coffee and tea. 

Cal'orie, the quantity of heat that will raise the temperature of four 
pounds of water very nearly one degree Fahrenheit. 

Capillaries, the microscopic blood tubes that connect the arteries 
and the veins. 

Carbohy'drates, starches and sugars. 

Car'bon, a substance found in every living thing; charcoal. 

Car'bon dioxide, a gas formed by burning or oxidizing carbon. 

Car'bon monoxide, a poisonous gas produced by imperfect burning. 
It is in the exhaust gases of an automobile. 

Carrier, a well person who produces disease germs in his body. 

Car'tilage, tough flesh resembling softened bone; gristle. 

Cells, the units of living matter in an animal or plant; the smallest 
bits of living matter which can carry on the processes of life. 

Cerebellum, the rounded part of the brain under the hinder part of 
the cerebrum. 

Cer'ebrum, the large rounded mass forming the upper part of the 
brain. 

Certified milk, pure, clean milk produced under the oversight of a 
board of doctors. 

Cesspool, an underground tank for receiving sewage. 

Chlo'rine, a gas used in purifying water. 

Cho'roid coat, the dark coat on the inside of the eyeball. 

Circulation, the flow of blood through the body. 

Coagula'tion, the process by which a liquid becomes jellylike ; clotting. 

Cold, any mild form of infectious disease. 

Cold storage, the keeping of articles in a room artificially cooled in order 
to preserve them in a fresh state. 

Connec'tive tissue, the tough fibers that hold cells in place. 

Contact, a person who has been associated with a sick person or a 
carrier in such a way that he may have caught his disease. 

Contrac'ture, a permanent contraction of a muscle. 

Convul'sion, a contraction of all of the muscles of the body, due to 
sickness. 

Cor'nea, the clear window in the front of the eyeball. 

Cor'puscles, the cells that float in the liquid part of the blood. 

Culture, an artificial growth of bacteria or other microscopic living 
things. 

Decay', the process by which matter once living slowly goes to pieces 
and is finally returned to the soil and air. It is usually caused 
by bacteria or molds. 


GLOSSARY 


419 


Der'mis, the true skin. 

Di'aphragm, the sheet of muscle extending across the body near the 
waistline, and separating the chest from the abdomen. 

Diges'tion, dissolving and changing food to forms that may enter the 
blood. 

Diphthe'ria, a throat disease caused by the growth of diphtheria 
bacteria. 

Disinfectant, a substance that will kill disease germs. 

Dis'locate, to slip the ends of two bones of a joint past each other; 
to put out of joint. 

Distillation, separating alcohol from a boiling liquid by collect¬ 
ing the steam and cooling it. 

Emul'sion, a milky liquid in which small drops of fat float in water. 

Enam'el, the hard, white coating on the outside of a tooth. 

En'zyme, a substance on which the digestion of food depends. 

Epidem'ic, a disease that attacks a large number of people at once. 

Epider'mis, the thin, outer covering of the skin, composed of epithe¬ 
lium. 

Ep'ilepsy, convulsions due to a brain disease. 

Epithelium, the cells forming the outer coating of the skin, the lining 
of the air tubes and digestive organs, and glands. 

Esoph'agus, the tube that conducts food from the throat to the 
stomach. 

Eusta'chian tube, the air tube leading from the throat to the middle 
ear. 

Excretions, the oxidized substances and waste matters of the body. 

Fermentation, changing sugar in a liquid to carbon dioxide and 
alcohol. 

Filter, a tank of sand used for removing impurities from water. 

Fo'cal infection, disease germs which grow in a small part of the 
body for a long time and send mild poisons through the body. 

Fo'cusing, changing the shape of the lens of the eye in order to see 
clearly. 

For'malin, a colorless liquid used for killing bacteria and disease 
germs. 

Frontal si'nus, the hollow space in the bone behind the eyebrows. 

Funny bone, the nerve on the inner side of the tip of the elbow. 

Gan'glia, collections of nerve cells in the sympathetic nervous system. 

Garbage, waste food and other substances thrown away from the 
kitchen. 

Gas trap, a portion of a waste pipe bent sharply in order to hold water 
and prevent sewer gas from flowing through the pipe. 

Gas'tric juice, the liquid produced by the stomach to digest food. 


420 


GLOSSARY 


Gland, a collection of tubes that remove substances from the blood, 
or form new substances out of the blood. 

Gly'cogen, a form of sugar which is stored in the liver. 

Goi'ter, an enlargement of the thyroid gland. 

Haemoglo'bin, the red coloring matter of the blood. 

Hu'merus, the bone in the upper half of the arm. 

Humidity, the wetness or dryness of the air. 

Hy'drogen, a substance that forms a part of every living thing. Pure 
hydrogen is a gas, and forms water when it is burned. 

Hydropho'bia, a disease of the brain usually caught from mad dogs; 
rabies. 

Hy 'giene, the study of the care of the body. 

Hysterics, a mental sickness accompanied by much laughing or 
crying. 

Idiot, a grown person who has the mind of a baby. 

Im'becile, a grown person who has the mind of a four-year-old child. 

Immu'nity, the ability of the body to prevent the growth of disease 
germs in the flesh or blood. 

Incuba'tion period, the time that elapses between taking disease 
germs into the body and the onset of the sickness. 

Infec'tion, the taking of germs of a disease into the body. 

Infectious diseases, forms of sickness due to the growth of disease 
germs in the flesh or blood ; diseases which one person can catch 
from another. 

Insanity, a mental disease or disorder which causes the sick person 
to act in a disorderly manner. 

Intem'perance, satisfying a false appetite. 

Intestine, the part of the food tube below the stomach. 

Intoxication, a poisoning by alcohol. 

I'ris, the colored curtain in the front part of the eyeball. 

Isolation, keeping a sick person away from those who are well and 
have not had his disease. 

Lac'teals, the lymph tubes that take digested fat from the intestine. 

Lactic acid, the sour substance in sour milk. 

Lar'ynx, the box of cartilage in which the sound of the voice is formed. 

Lens, the part of the eyeball that forms clear images in the eye. 

Lig'aments, the tough bands of flesh that bind the bones of a joint 
together. 

Liver, the gland that manufactures bile. 

Lymph, the liquid that passes from the blood through the sides of 
the capillaries to feed the cells of the body. 

Lymphatics, the fine tubes that conduct lymph toward the heart. 


GLOSSARY 


421 


Maggot, a young fly in its wormlike stage. 

Medulla, the part of the brain next to the spinal cord. 

Metab'olism, the processes of upbuilding and destruction by which 
life is maintained in a living body. 

Minerals, the part of the body that is left as ashes when the body is 
burned. 

Molars, the double teeth. 

Mold, microscopic threadlike plants that grow in damp places and 
often produce a velvetlike covering on food and clothing. 

Mor'phine, the narcotic poison in opium. 

Motor nerves, nerves that carry messages away from the brain or 
spinal cord. 

Mu'cous membrane, the skinlike lining of the air passages and di¬ 
gestive tube. 

Mu' cus, the substance, like white of egg, formed by mucous mem¬ 
branes. 

Muscle, a bundle of cells that produce a motion of some part of the 
body; lean meat. 

Narcot'ic, a drug that dulls the mind and produces sleep. 

Nerve, a thread or string of flesh that carries messages between the 
brain or the spinal cord and another part of the body. 

Nic'otine, the principal poisonous substance in tobacco. 

Ni'trogen, the gas that forms four fifths of the air. 

Nu'cleus, the dark-colored spot seen in most cells. 

O'pium, the dried juice of a poppy plant. It is a narcotic, and pro¬ 
duces sleep. 

Organ, a part of the body which does a special kind of work. 

Osmo'sis, the mixing of two liquids or gases when separated by a thin 
sheet of tissue. 

Oxida'tion, the union of oxygen with a substance ; burning. 

Ox'ygen, a gas that forms one fifth of the air. It unites with other 
substances in a fire and other forms of oxidation. 

Pan'creas, a gland that produces one of the digestive juices. 

Pancreat'ic juice, the digestive liquid formed by the pancreas. 

Panic, a fear that leads a crowd to act in a dangerous manner. 

Papil'lae, the tiny projections that form lines and patterns on the 
skin, especially on the palms of the hands. 

Par'alyzed, unable to move a part of the body. 

Paramo'cium, a microscopic animal composed of a single cell. 

Pas'teu“ize, to heat milk or other substance to about 145 0 F. for 
about 30 minutes in order to kill the bacteria that it may contain. 

Perios'teum, the skinlike covering of a bone. 

Peristal'sis, the motions of the digestive organs by which food is 
forced down them. 


422 


GLOSSARY 


Perspira'tion, sweat. 

Phar'ynx, the muscular bag forming the back part of the throat. 

Physiol'ogy, the study of the work of the body. 

Plague, a dangerous disease that is spread mostly by fleas that 
infest rats. 

Plas'ma, the liquid part of the blood ; serum. 

Pores, the openings of the sweat glands. 

Pro'tein, the substance, like white of egg, that forms the living part 
of every plant and animal. 

Proud flesh, new flesh growing on a sore spot faster than the epider¬ 
mis can cover it. 

Pupil, the round hole in the iris admitting light into the eye. 

Pus, the creamy matter flowing from a wound. It consists mainly 
of white blood cells killed by disease germs. 

Quarantine, preventing the spread of an infectious disease by keep¬ 
ing the sick away from the well. 

Ra'bies, hydrophobia. 

Ra'dius. the bone on the thumb side of the arm below the elbow. 

Re'flex action, the action of the brain or spinal cord made in response 
to a sensory message. 

Res'ervoir, a very large tank in which water is stored. 

Respiration, breathing and the oxidation in the body. 

Ret'ina, the inner coating of the eyeball. It contains the nerves of 
sight. 

Sali'va, the digestive fluid in the mouth. 

Sanatorium, a home in which unhealthy persons are taught how to 
live healthful lives. 

Scarlet fever, an infectious fever in which there is redness of the skin, 
followed by a peeling of the epidermis. 

Scrof'ula, a disease in which the lymph glands of the neck are en¬ 
larged. 

Scurvy, a disease caused by the lack of fresh vegetables and fruits. 

Seba'ceous gland, a gland which produces oil to soften the skin and 
hair. 

Secre'tion, the substance formed by a gland. 

Sen'sory nerves, the nerves that carry messages to the spinal cord 
or brain. 

Septic tank, a tank in which the solid matters of sewage decay and 
are liquefied. 

Se'rum, the liquid part of blood. 

Sewage, waste water and slops from kitchens, laundries, and bath¬ 
rooms. 

Shock, sudden weakness or sickness due to an injury. 

Skel'eton, the bony framework of the body. 


GLOSSARY 


423 

Spinal cord, the part of the nervous system that is contained inside 
the backbone. 

Spores, the seedlike particles of dust produced by molds and many 
other plants. 

Spu'tum, thick mucus removed from the air tubes. 

Ster'ilize, to heat a substance so as to kill the bacteria in it. 

Ster'num, the breastbone. 

Stim'ulant, a substance that acts upon the body like a whip. 

Stomach, the enlarged part of the digestive tube that receives food 
after it has been swallowed. 

Streptococ'cus, a common form of disease germ which produces 
severe forms of tonsillitis and other diseases. 

Sympathetic system, the part of the nervous system that controls 
the action of glands and involuntary muscles. 

Syno'vial fluid, the fluid contained in the joints. 

Tartar, a brown crust that often forms on unclean teeth. 

Tet'anus, a disease in which the muscles of the whole body are con¬ 
tracted ; lockjaw. 

Thermom'eter, an instrument for measuring degrees of temperature. 

Tho'rax, the part of the body surrounded by the ribs. 

Thy'roid gland, a gland in the front of the neck. It has an impor¬ 
tant effect on oxidation in the body. 

Tissue, a collection of cells having a special work to do. 

Tonsillitis, an infectious soreness of the tonsils. 

Tonsils, two masses of flesh growing in the sides of the throat. 

Tra'chea, the air tube leading from the throat to the lungs. 

Tracho'ma, an infectious disease of the eyelids. 

Tri'ceps, the muscle that bends the elbow. 

Tuberculo'sis, a disease in which white bodies, like pinheads, form in 
the flesh; consumption. 

Ul'na, the bone on the little finger side of the forearm. 

U'rea, a waste substance in the urine. It contains the waste nitro¬ 
gen of the body. 

U'rine, the liquid secreted by the kidneys. 

Vaccina'tion, protecting the body against smallpox by causing the 
germs of cowpox to grow in the body; also protecting til'" body 
against other diseases by injecting dead germs of the disease into 
the body. 

Ventila'tion, keeping up a flow of fresh air into a room. 

Ven'tricles, the two cavities in the lower end of the heart; they form 
the greater part of the heart. 

Vermin, insects and small animals that are troublesome to man. 


424 


GLOSSARY 


Vil'li, the small projections of mucous membrane that take up food 
from the intestine. 

Vi'tamins, food substances that are needed in order that the body 
may make use of its building and fuel foods. They are abundant 
in milk and green vegetables. 

Vocal cords, two bands of flesh by means of which the sounds of the 
voice are formed. 

Wiggler, a young mosquito while it lives in the water. 

Yeast, microscopic plants that change sugar to alcohol and carbon 
dioxide. 


INDEX 


. Abscess of teeth, 309 
Absorbent cotton, 122 
Absorption, 265 
Accidents, hi 
A cetic acid, 60 
Adenoids, 143, 397 
Adulteration, 297 
Air, 33, 129, 148 
analysis of, 158 
and disease germs, 316 
Air sacs, 130 
Albino, 188 
Albumin, 31 
Alcohol, 59 

cause of insanity, 388 
cause of poverty, 388 
effects on accuracy, 91 
brain, 386 
crime, 388 
endurance, 91 
muscles, 91 
oxidation, 146 
strength, 91 
not a food, 243 
Alertness, 90 
Algae, 24 

Amendment to Constitution, 63 

Amino acids, 255 

Analysis of air, 158 

Analysis of water, 222 

Anatomy, 18 

Ankles, weak, 85 

Antitoxin, 125, 322, 339, 341 

Antrum, 305 

Aorta, 96 

Apoplexy, 109 

Appetite, 58 

Aqueduct, Croton, 15 

Arithmetic problems, 161, 165, 249 


Arteries, 96 

expansion of, 108 
hardening of, 109 
Artificial respiration, 144 
Ashes, 30 

Assimilation, 265, 268 
Astigmatism, 403 
Attention, 90, 380 
Auricle, 100 

Automobile, exhaust gas of, 159 

Backbone, 69, 74 
Bacteria, 40 
Balanced diet, 247, 287 
Bandage, 121 
Bathing, 194 
Beans, 280 
Bedbugs, 236 
Bedroom, 164 
Bee stings, 227 
Beefsteak, 26 
Biceps, 80 
Bile, 258 
Bill of fare, 287 
Bleeding, 116 
how to stop, 119 
Blister, 187 
Blood, 94 

Blood poisoning, 45 
Blood pressure, 107 
Board of health, 54 
Boils, 44 

Bone, 23, 68, 76, 125, 353 

Botulism, 298 

Bowel, 257 

Bowlegs, 74 

Brain, 22, 361, 372 

Bread, 279 

Breathing, 131 

425 



INDEX 


426 

Broken bone, 76, 125 
Bronchi, 130 
Bronchitis, 345 
Brushing teeth, 308 
Butter, 286 

Callus, 185 
Calorie, 171, 245 
Camera, 401 

Candle, 150, 157, 169, 172 
Canning, 42, 290 
Capillaries, 99 
Carbohydrates, 240 
Carbon, 34 
Carbon dioxide, 34, 132, 158, 198 
Carbon monoxide, 158 
Carrier, 315, 340 
Cartilage, 73 
Catarrh, 143 

Cells, 23, 73, 82, 94, 99, 185, 266, 

363 

Cement, 307 
Cereals, 278 
Cerebellum, 373 
Cerebrum, 374 
Certified milk, 293 
Cesspool, 205 
Cheese, 286 
Chest, 131 
Chivalry, 90 
Chlorine, 220 
Cholera, 14 
Chorea, 303 
Choroid coat, 400 
Cider, 60 

Cigarettes, 65, 389 
Circulation, 21, 102 
Cleanliness, 46 
Clot, 95 

Clothing, 141, 180 
Coagulation, 31 
Coal gas, 158 
Cockroaches, 235 
Cocoa, 287 
Coffee, 286 


Cold-blooded animals, 174 
Colds, 166, 177, 346 
Cold storage, 291 
Colon bacilli, 223 
Communicable diseases, 37, 313 
Complexion, 192 
Connective tissue, 26, 73, 82 
Consciousness, 366 
Consumption, 352 
Contact infection, 318 
Contacts, 330 

Contagious diseases, 37, 313 
Contractions of muscles, 81, 
192 

Contractures of muscles, 86 

Convulsions, 126 

Cooking, 254, 300 

Cooperation, 90 

Cornea, 400 

Corns, 186 

Corpuscles, 94 

Cotton, absorbent, 122 

Courtesy, 379 

Cowpox, 324 

Cream, 285 

Cripples, 85 

Cross-eye, 404 

Croton aqueduct, 15 

Cultures, 313 

Curiosity, 115 

Date of onset, 329 
Deafness, 396 
Death rate, 12, 55 
Decay, 37, 203 
Decay and disease, 49 
Deep breathing, 134 
Dentine, 306 
Department of health, 48 
Dermis, 184 
Desserts, 301 
Diaphragm, 131 
Digestion, 21, 254 
Diphtheria, 322, 337 
Dirt, 294, 319 



INDEX 


427 


Disease germs, 37 
in air, 155 

in dirt, 123, 167, 319 
in food, 299 
in teeth, 307 
in tonsils, 144 
in water, 215 
in wounds, 122 
on hands, 300, 335 
Disinfection, 334 
Dislocation, 71 

Disposal of sewage, 43, 203, 206 
Distillation, 61 
Division of cells, 25, 41 
Division of labor, 20 
Dog catcher, 238 
Drafts, 166 
Dressings, 121 
wet, 124 
Drinking, 262 
Drinking cups, 223 
Drinking fountain, 224 
Drugs, 66 
Drunkenness, 61 
Drying food, 290 
Dumbness, 413 
Dust, 154, 167, 317 

Ear, 394 
Earthworm, 97 
Earwax, 398 
Eating, 261 

Education in public health, 17, 53,168 

Eggs, 284 

Electric shock, 146 

Emergencies, hi 

Emergency dressings, 124 

Emulsion, 256 

Enamel, 306 

Endurance, 90 

Enzymes, 256 

Epidemic, 13, 48 

Epidermis, 184 

Epilepsy, 126 

Epithelial cells, 25, 27, 185 


Epithelium, 27 
Esophagus, 256 
Eustachian tube, 396 
Excretions, 22, 197 
and disease germs, 201 
of intestine, 199, 243, 260, 268 
of kidneys, 199 
of lungs, 132 
of nose and throat, 201 
of skin, 198 

Exercise, 84, 87, 134, 180 
Expansion of chest, 135 
Expiration, 131 
Eye, 400 
defects, 402 
diseases, 408 

Face muscles, 82 
Fainting, 126 
Fair play, 90 
Farsightedness, 402 
Fat, 31, 256 
Fatigue, 88, 382 
Feeble mindedness, 385 
Feet, 85 

Fermentation, 40, 59 

Ferments, 256 

Fever, 171 

Filter, 204, 208, 218 

Filtration, 204, 218 

Finger prints, 189 

Fingers, and infection, 335 

Fire, 33 

Fire drill, 113 

Fireplace, 179 

Fire prevention, 112 

First aid, 115 

Fish, 283 

Fits, 126 

Flat feet, 85 

Flavorings, 242 

Fleas, 14, 236 

Flies, 228, 335 

extermination of, 231 
flyblows, 231 




INDEX 


428 

Floors, 168 
Flour, 279 
Flyblows, 231 
Focal infection, 303, 309 
Focusing, 402 
Food, 138, 240 
composition of, 247 
groups, 278 
poisoning, 297 
relation to oxygen, 138 
values, 243 
Foodstuffs, 276 
Formalin, 335 
Fortitude, 90 
Foul air, 148, 151 
and lights, 156 
Freckles, 188 
Fruit, 281 
Fuel food, 241 
Fumigation, 335 
Funny bone, 392 

Games, 90 

Garage, gas in, 159 

Garbage, 209 

Gas trap, 209 

Gastric juice, 258 

Gauze dressings, 122 

Gills, 132 

Glands, 27, 258 

Glucose, 256 

Glycogen, 267 

Goiter, 273 

Goose flesh, 192 

Granulated eyelids, 409 

Gray matter, 363 

Great white plague, 16, 351 

Gristle, 70 

Growing pains, 75, 281 
Growth, 20, 84, 270 
Gums, 309 
Gymnasium, 84, 90 

Habits, 66, 377 
Haemoglobin, 95 


Hair, 191 

Handkerchiefs, 202 
Hard water, 214 
Headache cures, 66 
Health, 10, 87, 134, 379 
Health department, 48 
Health officer, 54 
Hearing, 394 
Heart, 21, 100, 303 
and exercise, 106 
disease of, 105, 303 
Heat, 33, 133, 170 
Heating houses, 179 
Heat stroke, 175 
Hibernation, 174 
Hip-joint disease, 75 
Honesty, 90 
Hookworm disease, 344 
House slops, 205 
Humerus, 69 
Humidity, 175 
Hunchback, 75 
Hydrogen, 35 
Hydrophobia, 45, 237, 321 
Hygiene, 18 
Hysterics, 127 

Ice, 221 

Immunity, 321, 336 
Impurities in air, 149 
Impurities in water, 214 
Incubation period, 321 
Infantile paralysis, 86 
Infection, 313 
routes of, 317 

Infectious diseases, 37, 48, 313 
list of, 44, 329 
Insanity, 385 
Insects, 227, 316 
Inspiration, 131 
Intemperance, 59 
Intestine, 21, 199, 257 
Intoxication, 61 
Involuntary muscle, 79, 259 
Iodine, 123 




INDEX 


429 


Iris, 400 
Iron, 95 
Isolation, 333 

Jaundice, epidemic, 237 
Joints, 69, 81, 86 
Jugular vein, 97 

Kidneys, 22, 199 

Lacteals, 267 
Lactic acid, 292 


Mold, 38, 169 
Morphine, 65 
Mosquitoes, 232 
Motor nerves, 363 
Mouth, 303, 305 
cleansing the, 306 
Mouth breathing, 141 
Mouth digestion, 261 
Mucous membrane, 195 
Mucus, 195 
Mumps, 257 
Muscle, 22, 79 


Larynx, 412 
Lens, 401 
Leprosy, 16 
Lice, 14, 235 
Life, 20 
Ligaments, 70 
Lights, 156, 406 
Lime, 30, 72, 76, 109 
Liver, 22, 267 
Lockjaw, 125 
Loyalty, 90 
Lungs, 21, 129, 198 
Lymph, 103 
Lymphatics, 104 

Maggots, 231 
Malaria, 45, 186, 232, 320 
Manners, 263, 379 
Measles, 342 

Measurement of chest, 135 
Measurement of heat, 171 
Meat, 283 
Medulla, 373 
Memory, 375 
Metabolism, 273 
Mice, 237 
Microscope, 100 
Milk, 284, 292 
Mind, 9, 56, 375 
Minerals, 30, 198, 241, 307 
Mineral water, 214 
Moisture in air, 153, 175, 178 
Molar tooth, 311 


Nails, 192 
Narcotics, 58, 62 
Nearsightedness, 403 
Nerve cells, 363 
Nerves, 22, 362 
Nervousness, 380 
Nervous system, 22, 361 
Nicotine, 63 
Nitrogen, 35, 148 
Nits, 235 

Nose, 142, 303, 393 
Nosebleed, 121 
Nourishment, 270 
Nucleus, 26 
Numbness, 182 
Nuts, 280 

Obedience, 90, 379 

Odor test for foul air, 153, 157 

Odor test for milk pail, 294 

Oil glands, 190 

Onset, date of, 329 

Opium, 65 

Optic nerve, 401 

Organ, 20 

Osmosis, 265 

Outdoor air, 149 

Oxidation, 33, 38, 83, 132, 170 

Oxygen, 21, 33, 150 

Pain, 66 , 365, 302 

Panama, and yellow fever, 16, 235 



43 ° 


INDEX 


Pancreas, 21, 258 
Panic, 113 
Papilla, 189 
Paralysis, 86, 364 
Paramecium, 23 
Pasteurize, 296 
Pasteur treatment, 238 
Patent medicines, 60 
Peas, 280 
Periosteum, 76 
Peristalsis, 259 
Persistence, 90 

Perspiration, 27, 174, 190, 198 

Pestilence, 13 

Pharynx, 256 

Physicians, n 

Physiology, 18 

Pimples, 44, 96, 193 

Plague, 13, 237 

great white plague, 16, 351 
Plasma, 94 
Playgrounds, 90 
Plymouth colonists, 13 
Pneumonia, 345 
Police power, 52 
Poliomyelitis, 86 
Pond alga, 24 
Poor nourishment, 270 
Poppy plant, 65 
Pore, 27 
Posture, 86, 140 
Potash, 31 
Potatoes, 280 
Power, 34, 84, 133 
Prickly heat, 190 
Prohibition, 62 

Protein, 31, 240, 243, 255, 268 

Proud flesh, 187 

Public drinking cups, 223 

Public health, 51 

Pulmotor, 146 

Pulse, 102, 116 

Pupa, 231 

Pupil, 400 

Purification of water, 220 


Pus, 123 

Putrefaction, 203 

Quarantine, 332 

Rabies, 237 

Radial artery, 96 

Radiators, 179 

Radius, 69 

Rats, 14, 237 

Red blood cells, 95/131 

Reflex action, 367 

Regulation of blood flow, 105 

Regulation of temperature, 173 

Relaxation, 89, 384 

Rennet, 286 

Reservoirs, 218 

Respect for others, 90, 379 

Respiration, 21, 129 

Respirators, 155 

Responsibility, 90 

Rest, 89, 383 

Retina, 401 

Rheumatism, 303 

Ribs, 131 

Rickets, 75, 242 

Rotting, 37 

Round shoulders, 86, 140 
Routes of infection, 317, 335 

Safety first, hi 
S aliva, 257 
Salivary glands, 257 
Salt, 31 

Salt in water, 222 
Sanatorium, 359 
Sand plots, 208 
Sanitary survey, 221 
Scab, 187 
Scarlet fever, 341 
Schick test, 341 
School and diseases, 337 
Scrofula, 353 
Scurvy, 75, 281 
Secretion, 28 



INDEX 


43 i 


Self-control, go 

Stomach ache, 260 

Senses, 365, 391 

Stomach and heart disease, 106 

Sensory nerves, 365 

Streptococcus, 299 

Septic tank, 208 

Strong drink, 59 

Serum, 94 

Stuttering, 414 

Sewage, 203, 206 

St. Vitus’s Dance, 303 

Sewer, 206 

Suboxidation, 138 

Shellfish, 284 

Sugar, 32 

Shivering, 181 

Sunshine, 168, 178 

Shock, 115 

Sunstroke, 175 

Sight, testing the, 404 

Sweat, 27 

Sinuses, 305 

Sweeping, 167 

Skeleton, 68 

Swimming, 114 

Skim milk, 285 

Sympathetic system, 369 

Skin, 184, 198, 316 

Synovial fluid, 71 

Skin graft, 187 


Skull, 68 

Tan, 188 

Sleep, 165, 383 

Tartar, 309 

Sling, 120 

Taste, 263, 393 

Slipper animalcule, 23 

Tea, 286 

Slops, 203 

Team work, 90 

Smallpox, 16, 324 

Tears, 408 

Smell, 393 

Teeth, 306 

Smoke, 33 

Tendon, 81 

Soda, 31 

Tetanus, 125 

Soda water, 34 

Thermometer, 157, 171 

Sodium chloride, 222 

Thinking, 375 

Soft water, 214 

Thoracic duct, 267 

Sore throat, 299, 345 

Thorax, 131 

Souring of milk, 292 

Thyroid gland, 273 

Spectacles, 403 

Tissues, 26 

Speech, 413 

Tobacco, 63, 91, 389, 410 

Spinal cord, 22, 361, 367 

Tone of voice, 415 

Spine, 68 

Tongue, 306, 413 

Spitting, 203, 355 

Tonics, 60, 275 

Splint, 77 

Tonsillitis, 144, 338, 345 

Spores, 39 

Tonsils, 143, 304 

Sprain, 71', 126 

Tool grinding, 155 

Sputum, 354 

Touch, 391 

Stammering, 414 

Tourniquet, 118, 120 

Starch, 240 

Trachea, 130 

Sterilize, 296 

Trachoma, 409 

Stews, 301 

Trap, gas, 209 

Stimulants, 62 

Triceps, 80 

Stomach, 21, 257 

Tuberculosis, 16, 351 



432 


INDEX 


Typhoid fever, 16, 229, 324, 343 
Typhus fever, 13, 235 

Ulna, 69 
Urea, 35, 198 
Uric acid, 35 
Urine, 199 

Vaccination, 323 
Vaccines, 323 
Vacuum cleaner, 167 
Valves of heart, 101, 106 
Valves of veins, 97 
Vegetables, 280 
Vein, 97 
Ventilation, 161 
Ventilators, 164 
Ventricle, 100 
Vermin, 227 
Villi, 267 
Vinegar, 60 
Vital spirits, 28 
Vitamins, 242, 286 
Vocal cords, 412 
Voice, 412 


Voluntary muscles, 79 
Voluntary work, 22 
Vomiting, 260 

Warmth and exercise, 180 
Warmth and foul air, 152 
Wastes of the body, 197 
Water, 30, 35, 198, 212 
examination of, 221, 222 
manufacture of, 35 
supply of, 212 
Weather, 178 
Wells, 216 
Wet dressings, 124 
White blood cells, 96, 321 
White of egg, 31, 266 
Whooping cough, 343 
Wigglers, 233 
Wind, 149, 178 
Windpipe, 129 
Wine, 60 

Wounds, i2T, 123 
Yeast, 39, 59 

Yellow fever, 16, 232, 233, 320 






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